I'm assuming your 'power controller' is just a triac-based dimmer circuit. These are not suitable for driving inductive loads, since they simply 'chop up' the input voltage, resulting in weird spikes and all kinds of nasty things on the in and output of your transformer. Other than changing the entire design to a switch-mode supply, a variac is your best option.
Yeah, thought the same. The datasheet on that power controller specifies that it is suitable for phase controllable inductive loads, but transformers could still be an issue. I think a mains synchronized triac could work, but couldnt find one quickly available. The full bridge rectifier that is after the transformer also causes some nasty current harmonics which may also complicate things. STM application note AN308/0289 explains it quite nicely and shows a solution
Right, that should be the simplest and most robust solution. It is very common among telsa coil / high voltage enthusiasts to use those. A variable transformer doesn't care much about "dirt" that's fed back from the load- and even if this is perhaps not a bad idea, it doesn't have to be an more expensive isolating variac but an autotransformer(Spartrafo) will do.
Triacs do work for inductive loads. They just need to be controlled the right way, there are power supplies out there that use a triac circuit on the primary of the transformer as pre regulation before the linear stage to minimize losses.
@@Alexander470815 Sure! With tricas inductive loads should be switched on within the sine-wave and switched of at zero power (no current flow), if I remember correctly. Doing this with a home-backet circuit requires some thinkering, correctly designed snubbers and so on. Commercial ones aren't exactly cheap (as far as I remember / without searching). A Thalheimer ESS 104 230V 1kVA variac is about 130€ new - I suspect a used one will be much cheaper. Edit: Ok, back in the days I tried to control a 20A 400V modified welding transformer for inductive heating of big roller bearings.. ;)
@@poldiderbus3330 For just on/off control you want to turn transformers on at peak voltage. Turn on at zero crossing will result in a huge current spike due to saturation. You can not control the turn off time, it will turn of itself if the load current falls below the holding current. Only special SCR(GTO) might be turned off during current flow. A Microcontroller is easily able to control a triac, with that you can build a closed loop regulation as well.
Drilling through screws is actually very common practise when working with vacuum chambers. I have used them in the past and they work great. Espeacially when you need e-6mBar or lower pressures they are highly recommended. Various companies make them, but if you only need a few it might be easier to just make them yourself ;) Great video, keep up the good work!
You could probably minimize arcing from the screw holes by putting a larger fillet or chamfer on those holes, arcs tend to start at the sharpest part of an object
Good idea! But I really want to avoid having to pay for new PTFE insulators. I will try to use screw hole plugs and create a small hole in the middle so the air can escape.
Xometry hack for you guys regarding the two clamps at 18:01. Just order the entire part, and cut it in half with a hacksaw. There are a bunch of parts I have ordered where it is '1 part' but can be 2 or 3 with minor alterations, involving tools that you 'should' already have somewhere.
Nice attention to detail with the thread's shown as these 'trapped volumes' or ' virtual leaks' can be a PITA. We used to just carefully file the screw down one side great work !.....cheers.
A temporary solution until you get more corrosion resistant materials would be to attach a piece of zinc or aluminum to the non-vacuum side as a cathodic protection anode. Zinc isn't vacuum compatible as I recall, and the anodes tend to flake pieces off as they corrode, which is why it needs to be on the atmospheric pressure side. Or stuff desiccant packets into that hole where the condensation is forming to absorb it.
I built a 10kV @ 10mA AC supply for PD testing. It uses a 24V to 10kV potted transformer and TDA7294 amplifier IC to drive it. I just supply the amplifier with a set of switching supplies and input waveform from a function generator. This produces a very clean AC HV source up to 100W (amplifier needs some heatsinking). For arcing - this is always a challenge with HV in vacuum, especially medium vacuum where Paschen is a big risk. Your specific issue is more likely creepage across the PTFE, promoted by surface charges which increase the field strength over the insulator. This is evident by the burn marks you see. Switching to insulated screws will obviously remove exposed HV from this location. I have exposed clean, dry PTFE to excess of 20kV/mm over the surface at 1e-4 mbar with no problems. You'll be limited by contamination (metallic particles can intensify the field, even if they are floating - even insulating particles can cause problems). At high field strengths, you can also create cold field emitters which "paint" nearby insulators with charge and promote discharges. Try to prevent so called triple points, but it is difficult with your construction. Another problem you may face at intermediate pressures is Paschen, where a shorter P*D distance is preferred (long P*D, above the Paschen curve "danger zone" is difficult to achieve in a small chamber). As a solution, I have in many instances shielded the exposed fields to a distance much smaller (~5x safety factor) than the minimum Paschen distance at my worst case pressure. The Kapton tape will not solve the creepage problem, and maybe make things worse if there is a virtual leak - then you will pump this void through the worst case Paschen pressure and induce breakdown to the nearby grounded casing. Or, it just pumps down with the chamber. In this case, Kapton may be acting as a shield to prevent big discharges (as only the Kapton surface can capacitively charge to a voltage close to your screws and cause some small discharges). Good luck
Very cool project and it's a funny name, considering that magnetron means microwave oven in Dutch. You can actually buy vented screws (screws with a hole through them) exactly for the purpose of preventing virtual leaks. I used to buy them pretty cheap from an English company called Accu but that was before Brexit...
To deal with the corrosion passivate by treating with HF, phosphoric or boric acid, purge then add EDTA and polyethylene glycol to the DI water loop. If the water isnt going over HV then just use automotive antifreze mix. The industrial version of these use NaK as the coolant btw.
To eliminate the condensate, use a 'aquarium' air pump and a hose to blow out the cavity in the stem and yoke plate. if you put the pump in a container filled with desiccant you blow in dried air which would not contain any moisture to condensate.
Good idea! But I will first try to use cooling water at room temperature. The heat transfer works good so I don't really need the lower temperatures. That should hopefully take care of the condensation.
@@AdvancedTinkering just use warm water. We use 100 F water in our ion sources and ebgs as well as running water through our chamber walls this prevents condensation.
Very nice design. And very economic as well. If you want to use Festo hoses with more pressure, you can use tube fittings with an insert for the hose. There is also a variant of the Festo hoses that has a flexible aluminium inner layer, allowing for even higher pressures (and they can be bent to start on a shape you want by hand). I remember there being some issues with magnetic targets in magnetron sputtering, so I'm excited to see what you'll do with it.
Thank you! Yes I will probably switch to those cutting ring fittings and use a metal insert for the tube. It's the same setup I used to connect the tube to the gas flow meter. Using an iron target probably influences the magnetic field a lot. I honestly haven't done any research on sputtering magnetic materials. But I will before trying it.
I haven't seen the other video referred to with the comment claiming Festo push in fittings to not be good for high pressure, so I don't know what constitutes high pressure, but the push in fittings are typically rated up to 14bar. Swagelok fittings could also be considered - choose the right configuration and they're rated for 757 bar
It looks like you are suffering from galvanic corrosion between the copper and the steel parts. You may want to look into plating the copper component in a material that has less galvanic potential like nickel.
They'll also need to ensure any metals they choose for their magnetron is electrochemically compatible with the metal in their cooler's heat exchanger!
I might be wrong, but why not put a Teflon shim or an insulating gasket in between the copper and steel part...maybe that might solve the problem of galvanic corrosion.
One thing that could be done with this is to sputter coat a nuclespot or staticmaster static eliminator source with beryllium to make a reasonably strong but rather short lived neutron source. It works well for testing neutron measurement instruments but decays to nothing after about 3 years. About 60um of beryllium and a few um of gold on top. ❤
One thing that comes to mind about the arcing after reading some other comments talking about how a triac could be "chopping up" the voltage, is that maybe the sharp changes in voltage are acting like a flourescent bulb starter and you just so happen to be on the edge of it just constantly arcing, and the un-smoothed noise in the power feed happens to occasionally drift it past what is needed for it to arc (given how I understand the arcing to be unpredictable as far as timing goes). This, in tandem with the voltage spike that comes with an inflow of voltage (referencing AlphaPhoenix's video about the speed of electricity and talking about voltage wavefronts as they travel through conductors), could be occasionally just be throwing it over what is needed to arc. Note: I am not an electrical engineer, nor really even that educated on the topic. This is just an attempt to bodge together things I have seen through various youtube videos in an attempt to be helpful.
One solution for AC power control is the "shunted bridge" method. You basically hook a bridge rectifier in series with the transformer and you can use a simple power transistor to control it from the DC side. It might suffer the same issues as a triac under inductive load though.
You should probably have bleeder resistors on your power smoothing capacitors. They may have built-in bleeder resistors but don't count on it. Without bleeders, the caps can store a charge for a long time and discharge into you if you touch the wrong part, even when disconnected from power.
If you got some PTFE rod that fits into the air space above those screws, you could cut little plugs and either press-fit them in, or hold them in place with the kapton tape
10:40 You can make a coating on your installation, but you will need another such part.. Alternatively, you can impregnate the surface in contact with moisture with oil, or paint
Thank you a lot for the great suggestions! I could not find the plating solution on Amazon (germany) but I found a similar product. I think I will try that.
those bulkhead KF clamps remind me about a great fact, if you want to connect KF parts to plates, you can just download the cad files from some vacuum seller, and then 3D print them!
I think I remember seeing pictures of your clamps in the discord server. They looked great. I just wouldn't trust them when they have to hold something heavy.
Looking at the disassembled lower part of your magnetron and the problem with the Teflon insulating sleeves, I think I would simply remove some material from the lower part so that the screw heads/sleeves protrude better - or increase the diameter of the counterbores. I can't remember if you have access to a lathe(edit: no you don't..) or where you live - if you are near Bremen and interested, I could help. Edit: I mean on the other hand the location also does not matter much..
Thank you very much for that offer! But the problem is, that the bottom part could only be shortened by maybe 1-2 mm because the material at the opening for the centering ring of the O-ring is not thick enough. Since in the inside has a conical shape, you would increase the hole diameter if you take away more material. I hope you understand what I mean. But for a different project I may come back to that offer if you are still interested.
A possible (but potentially a little pricey) solution for the HV arcing issues might be replacing the metal screws with Al2O3 alumina screws if the force on them you need to get a proper seal is small enough.
Very interesting and thanks for a price breakdown, I'm always curious how much these projects cost. With your arcing screws have you considered trying plastic screws? They aren't anywhere near as strong but if I'm understanding your design correctly they only need to compress an o-ring. It's probably cheap enough that you could buy them just to try.
I thought the prices would be very interesting for many viewers. At least when watching videos, I often wonder what certain components might have cost. I initially wanted to use plastic screws. Since it seems to be the simplest solution. However, almost all screws you find are made of nylon, which is not optimal for vacuum applications because it absorbs a lot of water. That probably wouldn't be quite as bad at the pressures I’m sputtering at, but I couldn't find any nylon screws with the correct dimensions either. PTFE or PEEK screws would be optimal, but even very short screws are very expensive there.
@@AdvancedTinkeringyou have shown you are adept at making things yourself, so why not get some PTFE rod of the proper diameter and a tap and die set to thread your own screws? I see on McMaster Carr that PTFE rod is relatively cheap (cheaper than the sleeves you bought) and a decent tap and die set is about $100 but then you have those tools for future use. Thread the rod, cut it to length, cut a slot in for a flat head screwdriver or two for a Phillips and then you are good to go and nicely insulated.
only thing concerning me is you only switching one side of the mains supply, your power button should disconnect both live and neutral just to be safe, you never know if your outlet is reversed, and having the transformer be at 220v when you believe it's off could be dangerous if you forget
It might be a creep issue rather than arcing or breakdown. You could maybe try raising the height of inserts a bit, so there is more length for current to creep through.
The Kemo M028N is doing phase-control which is the AC equivalent of what "pulse width modulation" is for DC. It's not actually regulating the AC peak to peak voltage up or down with a smooth continuous sinusoidal waveform, it's chopping up the AC waveform (at the full input voltage) into discrete smaller chunks in time starting from the sine zero crossing. The chopped-up AC waveform is not going to work well with your step-up microwave transformer, which is why it's not working at all until you turn it all the way up and the power control module starts outputting the full ac waveform.
Thank you a lot for the explanation! That makes sense and other comments agree with you. It's a bit disappointing, that there is no small option that fits I side the housing of the power supply. Smaller variacs seem to be very expensive.
Your PSU voltmeter is probably reading about 20% high at full output voltage because your big resister will have a VCR (Voltage coefficient of resistance) of about -200PPM/volt (maybe more) meaning its resistance will be about 20% lower than marked at 1000V. The easiest solution to this issue is to put several resistors in series so that each sees a lower voltage, for example using 10 resistors with 100V across each would reduce your resistance drift to 2% which is similar to the analogue meter accuracy.
I am not sure of alloy used but I have seen many stainless steel pots which are magnetic and stores use a small magenta to prove it will work with induction stoves.
Should condensation continue to be a problem, you might circulate air via a small diameter tube, perhaps fenestrated, run alonside the wires and other tubes
A good idea! But I think I will first try do not use cooling water below room temperature, since It's not necessary. That should hopefully solve the issue.
Das Problem mit dem "power Controller" ist das ist im Prinzip ein PhasenANschnittsdimmer. (Triac, billig, alte Technik) Das heißt der schaltet die Sinuswelle erst ab einer gewissen Spannung ein. Wenn der Trafo nicht stark genug belastet ist schießt der einfach nach oben wo die Spitze der Sinuswelle ist und gibt Spannung ab. Erst wenn er genug gesättigt ist reicht die Leistung der abgehackten Sinuskurve nicht mehr aus die Spannung am Ausgang hoch zu treiben! (magnetische impendanz) Um die Spannung quasi im Leerlauf gut zu regeln brauchst du warscheinlich einen PhasenABschnittdimmer, die funktionieren mit Feldeffekttransistoren und schalten ab einer gewissen Spannung der Welle ab. Bin mir aber nicht sicher ob das schlagartige abschalten nicht auch hohe Spitzen verursacht, ist aber mit nem minimalen Balstwiderstand bestimmt hinzubekommen. Der Variac ist aber warscheinlich die geschmeidigste Lösung! 😄
Vielen Dank für diese sehr hilfreiche Erklärung! Ich denke ich werde vorerst bei dem Stelltransformer bleiben. Eventuell teste ich bei Gelegenheit mal einen Phasenabschnittdimmer.
Es gibt genug Labornetzteile die einen Phasenanschnitt Dimmer auf der Primärseite des Trafos als Vorregler benutzen, das funktioniert ohne Probleme. Dafür muss der Triac aber korrekt angesteuert werden, das geht mit diskreten Komponenten nur recht aufwändig. Erzeugt man die Zündimpulse elektronisch kann man auch induktive Lasten sinnvoll regeln.
@@AdvancedTinkering Phasenabschnitt ist keine gute Idee in Verbindung mit induktiven Lasten. Versucht man den Stromfluss zu unterbrechen quittiert das die Induktivität mit einem erhöhen der Spannung bis der "Schalter" durchschlägt. Bei elektronischen Schalten also eine mehr oder weniger schnelle Zerstörung. Phasenanschnitt ist schon das richtige wenn man Transformatoren steuern will. Aber es muss eben richtig gemacht werden. Ich habe sehr gute Erfahrungen damit gemacht Triacs mit einem Microcontroller anzusteuern. Muss man eben den Nulldurchgang der Spannung erkennen und einen Timer im Controller darauf synchronisieren. Damit kann man denn den Triac zum passenden Zeitpunkt zünden. Das geht recht feinfühlig und es wäre auch denkbar eine Rückkopplung einzubauen so dass man die abgegebene Spannung misst und somit konstant hält.
You could try* to put an iunno.... 100nf? capacitor across the power controls output.. it might trick it into "working" but a triac isnt a good way to run a transformer.
inverter microwave power supplies have pwm control of the output voltage and safety features that insure u cant power it on at full power and that there isnt a short built into a module that's lighter and smaller then a traditional mot
@@AdvancedTinkering yea there are videos on youtube about how to get them working but they arent very high quality. they tldr is that there is a 4 wire harness connected to the board besides the mains ac inputs. the wires r vcc(5volts) , gnd, pwm input(220hz i think?), and some feedback signal that u need to pull to ground with 10k resistor.the pwm to be less then ~30-40% duty cycle to turn it on then can be increased. theres a video of a guy who builds a 555 based solution and a different guy used an arduino but i just got a lcd pwm module that made it easy
Not quite a proper die grinder, but if it removes metal is a satisfactory way and dosen't kill the tool... I have been known to make ad-hoc lathes from hand drills, angle iron and a prayer. Welded a hole in a tank with a bottle pf propane, someones grandpas oxygen tank, and some tubing and coathangars. If it needs done now, you can do it now, but usually not correctly. If only temporary fixes weren't the most permanent.
You might have the wrong resistance value for the potentiometer. If you used a 10K ohm vs. a 100K ohm the curve of the output of the controller would be more linear
Is there a reason why those screws with the PTFE insulators need to be metal? Could they not be swapped out for PTFE screws (or even ceramic, but those are expensive and hard to get...)
Using plastic Screws (PTFE or PEEK) was my first approach but they are so expensive. Especially when they are not "standard size". Nylon screws are more affordable but it's not a good material for vacuum applications and I could not find the size I need.
What if you put the screws connecting the HV section to the base into some ptfe inserts in the holes in the HV block? If you make them expand into the holes like a hollow wall molly or an expanding concrete anchor. Then you would not need a metal to metal connection there.
At 6:09 you talk about the screw isolation. Why don't you get teflon rod and chop fitting plugs that go onto the screw heads? Cheap DIY-plugs shouldn't be too expensive to replace, even if every removal is destructive. You might get it working with teflon tubing as well.
That or have the pfte inserts extend a cm or so above the ground potential part. If you’re building your own based of the CAD files you can just extrude the ‘pipe’ section of the existing model a bit:)
Can't you just make longer PTFE insulators in order to increase the creepage distance? Since they would protrude from the bottom, it shouldn't matter if they had a longer shoulder that sticks out from the magnetron.
Fantastic, really well done. Can you or maybe someone in the comments send me specs/details on your power controller? I can't promise you anything other than I am not a time waster and it will bug the life out of me until its resolved, lol, I do love problem solving. Peace and best wishes from Ireland., take care mo chara.
Damn.. 1000 bucks for these simple parts.. Having a lathe you can do all this work.. If people needed all this more often, workshops would get rich Considering that this is made in China, it would cost more in the USA.. Although you would only need a dividing device and a drilling machine, everything else is done on a lathe, especially the fluoroplastic bushings
What’s the Benefit of putting the Magnetron into the Vacuum Chamber compared to feeding via a WaveGuide? Can the desired Field only be created on Top of the Magnetron?
I guess the teflon sleeves are so expensive because of the thin wall thicknesses?! Other than that they don't look very special?! .. hmm, ich weiß nicht.. außer scharfe Werkzeuge scheint man dafür nichts exotisches zu brauchen?
It's not the same as a magnetron in a microwave. But it's still called magnetron. You can look it up in the article/review I cited under the picture I have used. doi.org/10.1016/S0042-207X(99)00189-X But I understand the confusion. I am not sure where the name comes from.
@@AdvancedTinkering I figured it out. A conventional magnetron is quite applicable, but additional equipment is required, in the form of an ion cannon, and related equipment. The magnetron you use combines these two things in itself.
The power circuits and other technologies you're working with are too far outside my knowledge for me to contribute anything useful, but I do want to acknowledge the types of comments popping up for this video. Not only is your channel fascinating to watch (and you clearly know your stuff, as well as being a great presenter) but there are hundreds of people who genuinely seem to know what they're talking about chiming in and discussing what should be an extremely niche, nerdy topic. Next time anyone despairs over the state of the world and has the "oh god people are so stupid these days we're doomed" thoughts, just remember there are hundreds of people discussing high vacuum equipment, the best controllers for inductive loads and solutions to galvanic corrosion. There are some interesting people out there doing some pretty awesome things, and it's pretty cool that we get to stumble upon this stuff with a few minutes and an internet connection, not that long ago all this stuff was hidden away in universities and engineering teams
I'm assuming your 'power controller' is just a triac-based dimmer circuit. These are not suitable for driving inductive loads, since they simply 'chop up' the input voltage, resulting in weird spikes and all kinds of nasty things on the in and output of your transformer. Other than changing the entire design to a switch-mode supply, a variac is your best option.
Yeah, thought the same. The datasheet on that power controller specifies that it is suitable for phase controllable inductive loads, but transformers could still be an issue. I think a mains synchronized triac could work, but couldnt find one quickly available. The full bridge rectifier that is after the transformer also causes some nasty current harmonics which may also complicate things. STM application note AN308/0289 explains it quite nicely and shows a solution
Right, that should be the simplest and most robust solution. It is very common among telsa coil / high voltage enthusiasts to use those. A variable transformer doesn't care much about "dirt" that's fed back from the load- and even if this is perhaps not a bad idea, it doesn't have to be an more expensive isolating variac but an autotransformer(Spartrafo) will do.
Triacs do work for inductive loads.
They just need to be controlled the right way, there are power supplies out there that use a triac circuit on the primary of the transformer as pre regulation before the linear stage to minimize losses.
@@Alexander470815 Sure! With tricas inductive loads should be switched on within the sine-wave and switched of at zero power (no current flow), if I remember correctly. Doing this with a home-backet circuit requires some thinkering, correctly designed snubbers and so on. Commercial ones aren't exactly cheap (as far as I remember / without searching). A Thalheimer ESS 104 230V 1kVA variac is about 130€ new - I suspect a used one will be much cheaper. Edit: Ok, back in the days I tried to control a 20A 400V modified welding transformer for inductive heating of big roller bearings.. ;)
@@poldiderbus3330 For just on/off control you want to turn transformers on at peak voltage. Turn on at zero crossing will result in a huge current spike due to saturation.
You can not control the turn off time, it will turn of itself if the load current falls below the holding current. Only special SCR(GTO) might be turned off during current flow.
A Microcontroller is easily able to control a triac, with that you can build a closed loop regulation as well.
Drilling through screws is actually very common practise when working with vacuum chambers. I have used them in the past and they work great.
Espeacially when you need e-6mBar or lower pressures they are highly recommended.
Various companies make them, but if you only need a few it might be easier to just make them yourself ;)
Great video, keep up the good work!
The industry term for that is 'vented screws,' where I work any screw used in the vacuum has to be a vented screw.
You could probably minimize arcing from the screw holes by putting a larger fillet or chamfer on those holes, arcs tend to start at the sharpest part of an object
In my mind, it seems the easiest option for stopping the arcing is to just extend the ptfe inserts by ~4mm or so.
Good idea! But I really want to avoid having to pay for new PTFE insulators.
I will try to use screw hole plugs and create a small hole in the middle so the air can escape.
@@AdvancedTinkering can you not buy them pre made rather than getting custom ones made?
Using PTFE tube might also be an Idea. Also relatively cheap
I was about to suggest the same thing, then he mentioned the cost of the insulators. That would be painful to remake.
@@AdvancedTinkering PTFE heat shrink tubing
Xometry hack for you guys regarding the two clamps at 18:01. Just order the entire part, and cut it in half with a hacksaw. There are a bunch of parts I have ordered where it is '1 part' but can be 2 or 3 with minor alterations, involving tools that you 'should' already have somewhere.
That's a really great idea to reduce the cost of manufacturing! Thanks!
Nice attention to detail with the thread's shown as these 'trapped volumes' or ' virtual leaks' can be a PITA. We used to just carefully file the screw down one side great work !.....cheers.
A temporary solution until you get more corrosion resistant materials would be to attach a piece of zinc or aluminum to the non-vacuum side as a cathodic protection anode. Zinc isn't vacuum compatible as I recall, and the anodes tend to flake pieces off as they corrode, which is why it needs to be on the atmospheric pressure side. Or stuff desiccant packets into that hole where the condensation is forming to absorb it.
I built a 10kV @ 10mA AC supply for PD testing. It uses a 24V to 10kV potted transformer and TDA7294 amplifier IC to drive it. I just supply the amplifier with a set of switching supplies and input waveform from a function generator. This produces a very clean AC HV source up to 100W (amplifier needs some heatsinking).
For arcing - this is always a challenge with HV in vacuum, especially medium vacuum where Paschen is a big risk. Your specific issue is more likely creepage across the PTFE, promoted by surface charges which increase the field strength over the insulator. This is evident by the burn marks you see. Switching to insulated screws will obviously remove exposed HV from this location. I have exposed clean, dry PTFE to excess of 20kV/mm over the surface at 1e-4 mbar with no problems. You'll be limited by contamination (metallic particles can intensify the field, even if they are floating - even insulating particles can cause problems). At high field strengths, you can also create cold field emitters which "paint" nearby insulators with charge and promote discharges. Try to prevent so called triple points, but it is difficult with your construction.
Another problem you may face at intermediate pressures is Paschen, where a shorter P*D distance is preferred (long P*D, above the Paschen curve "danger zone" is difficult to achieve in a small chamber). As a solution, I have in many instances shielded the exposed fields to a distance much smaller (~5x safety factor) than the minimum Paschen distance at my worst case pressure.
The Kapton tape will not solve the creepage problem, and maybe make things worse if there is a virtual leak - then you will pump this void through the worst case Paschen pressure and induce breakdown to the nearby grounded casing. Or, it just pumps down with the chamber. In this case, Kapton may be acting as a shield to prevent big discharges (as only the Kapton surface can capacitively charge to a voltage close to your screws and cause some small discharges).
Good luck
Very cool project and it's a funny name, considering that magnetron means microwave oven in Dutch. You can actually buy vented screws (screws with a hole through them) exactly for the purpose of preventing virtual leaks. I used to buy them pretty cheap from an English company called Accu but that was before Brexit...
Incredible. Very underrated as of now. I look forward to seeing great growth for you
Thank you!
To deal with the corrosion passivate by treating with HF, phosphoric or boric acid, purge then add EDTA and polyethylene glycol to the DI water loop. If the water isnt going over HV then just use automotive antifreze mix. The industrial version of these use NaK as the coolant btw.
Magnets, vacuum, high voltage, plasma and beautiful machined/designed parts ❤
For insulation use Kapton tape over the plastic bushing, just make it taller with the tape, wounding 1-2 layer over the white bushing.
To eliminate the condensate, use a 'aquarium' air pump and a hose to blow out the cavity in the stem and yoke plate. if you put the pump in a container filled with desiccant you blow in dried air which would not contain any moisture to condensate.
Good idea! But I will first try to use cooling water at room temperature. The heat transfer works good so I don't really need the lower temperatures. That should hopefully take care of the condensation.
@@AdvancedTinkering just use warm water. We use 100 F water in our ion sources and ebgs as well as running water through our chamber walls this prevents condensation.
Very nice design. And very economic as well.
If you want to use Festo hoses with more pressure, you can use tube fittings with an insert for the hose. There is also a variant of the Festo hoses that has a flexible aluminium inner layer, allowing for even higher pressures (and they can be bent to start on a shape you want by hand).
I remember there being some issues with magnetic targets in magnetron sputtering, so I'm excited to see what you'll do with it.
Thank you! Yes I will probably switch to those cutting ring fittings and use a metal insert for the tube. It's the same setup I used to connect the tube to the gas flow meter.
Using an iron target probably influences the magnetic field a lot. I honestly haven't done any research on sputtering magnetic materials. But I will before trying it.
I haven't seen the other video referred to with the comment claiming Festo push in fittings to not be good for high pressure, so I don't know what constitutes high pressure, but the push in fittings are typically rated up to 14bar.
Swagelok fittings could also be considered - choose the right configuration and they're rated for 757 bar
It looks like you are suffering from galvanic corrosion between the copper and the steel parts. You may want to look into plating the copper component in a material that has less galvanic potential like nickel.
Why not plate the copper and the steel in nickel?
They'll also need to ensure any metals they choose for their magnetron is electrochemically compatible with the metal in their cooler's heat exchanger!
I might be wrong, but why not put a Teflon shim or an insulating gasket in between the copper and steel part...maybe that might solve the problem of galvanic corrosion.
One thing that could be done with this is to sputter coat a nuclespot or staticmaster static eliminator source with beryllium to make a reasonably strong but rather short lived neutron source. It works well for testing neutron measurement instruments but decays to nothing after about 3 years. About 60um of beryllium and a few um of gold on top. ❤
One thing that comes to mind about the arcing after reading some other comments talking about how a triac could be "chopping up" the voltage, is that maybe the sharp changes in voltage are acting like a flourescent bulb starter and you just so happen to be on the edge of it just constantly arcing, and the un-smoothed noise in the power feed happens to occasionally drift it past what is needed for it to arc (given how I understand the arcing to be unpredictable as far as timing goes). This, in tandem with the voltage spike that comes with an inflow of voltage (referencing AlphaPhoenix's video about the speed of electricity and talking about voltage wavefronts as they travel through conductors), could be occasionally just be throwing it over what is needed to arc.
Note: I am not an electrical engineer, nor really even that educated on the topic. This is just an attempt to bodge together things I have seen through various youtube videos in an attempt to be helpful.
One solution for AC power control is the "shunted bridge" method. You basically hook a bridge rectifier in series with the transformer and you can use a simple power transistor to control it from the DC side. It might suffer the same issues as a triac under inductive load though.
13:32 You can use helicoils in the taped holes they are pretty easy to install if you're worried about stripping the threads
3:42 *Louis Slotin liked this post*
@6:20 Easier solution: Teflon (and/or Delrin) plugs, cut from a rod of appropriate diameter. Up to you if you chose plugs with/without shoulders.
You should probably have bleeder resistors on your power smoothing capacitors. They may have built-in bleeder resistors but don't count on it. Without bleeders, the caps can store a charge for a long time and discharge into you if you touch the wrong part, even when disconnected from power.
If you got some PTFE rod that fits into the air space above those screws, you could cut little plugs and either press-fit them in, or hold them in place with the kapton tape
10:40 You can make a coating on your installation, but you will need another such part.. Alternatively, you can impregnate the surface in contact with moisture with oil, or paint
There's gold plating solution that you microwave and submerse your parts in.
Maybe that would work? Its cheap and on amazon, so its a dice roll.
Thank you a lot for the great suggestions! I could not find the plating solution on Amazon (germany) but I found a similar product. I think I will try that.
Dude this is incredible 🤯🙏✨
Thank you!
those bulkhead KF clamps remind me about a great fact, if you want to connect KF parts to plates, you can just download the cad files from some vacuum seller, and then 3D print them!
I think I remember seeing pictures of your clamps in the discord server. They looked great.
I just wouldn't trust them when they have to hold something heavy.
@@AdvancedTinkering theyve been holding my setup for a year now ^^ , altho yes, its more sorta a cheap option for attaching single gauges and stuff
You also can use vacuumscrews to fix your kf16 flansch
Looking at the disassembled lower part of your magnetron and the problem with the Teflon insulating sleeves, I think I would simply remove some material from the lower part so that the screw heads/sleeves protrude better - or increase the diameter of the counterbores. I can't remember if you have access to a lathe(edit: no you don't..) or where you live - if you are near Bremen and interested, I could help. Edit: I mean on the other hand the location also does not matter much..
Thank you very much for that offer! But the problem is, that the bottom part could only be shortened by maybe 1-2 mm because the material at the opening for the centering ring of the O-ring is not thick enough. Since in the inside has a conical shape, you would increase the hole diameter if you take away more material. I hope you understand what I mean.
But for a different project I may come back to that offer if you are still interested.
Thank you pcbway. The cnc prices are very reasonable.
A possible (but potentially a little pricey) solution for the HV arcing issues might be replacing the metal screws with Al2O3 alumina screws if the force on them you need to get a proper seal is small enough.
416ss would be an affordable option for magnetic stainless. Very easy to machine too. 17-4 and 15-5 if you want to go with the good stuff.
Thank you for letting me know!
Very interesting and thanks for a price breakdown, I'm always curious how much these projects cost. With your arcing screws have you considered trying plastic screws? They aren't anywhere near as strong but if I'm understanding your design correctly they only need to compress an o-ring. It's probably cheap enough that you could buy them just to try.
I thought the prices would be very interesting for many viewers. At least when watching videos, I often wonder what certain components might have cost.
I initially wanted to use plastic screws. Since it seems to be the simplest solution. However, almost all screws you find are made of nylon, which is not optimal for vacuum applications because it absorbs a lot of water. That probably wouldn't be quite as bad at the pressures I’m sputtering at, but I couldn't find any nylon screws with the correct dimensions either.
PTFE or PEEK screws would be optimal, but even very short screws are very expensive there.
@@AdvancedTinkering maybe make DIY screws? that's a big hassle tho
@@mark0305If you've done it a bunch, it's trivial. Working with teflon and/or PEEK is a bit tedious, however.
@@AdvancedTinkeringyou have shown you are adept at making things yourself, so why not get some PTFE rod of the proper diameter and a tap and die set to thread your own screws? I see on McMaster Carr that PTFE rod is relatively cheap (cheaper than the sleeves you bought) and a decent tap and die set is about $100 but then you have those tools for future use. Thread the rod, cut it to length, cut a slot in for a flat head screwdriver or two for a Phillips and then you are good to go and nicely insulated.
only thing concerning me is you only switching one side of the mains supply, your power button should disconnect both live and neutral just to be safe, you never know if your outlet is reversed, and having the transformer be at 220v when you believe it's off could be dangerous if you forget
Very good point! I will change that.
An easy solution to make the steel part more corrosion resistant and high vacuum compatible would be to just nickel plate it
It might be a creep issue rather than arcing or breakdown. You could maybe try raising the height of inserts a bit, so there is more length for current to creep through.
The Kemo M028N is doing phase-control which is the AC equivalent of what "pulse width modulation" is for DC. It's not actually regulating the AC peak to peak voltage up or down with a smooth continuous sinusoidal waveform, it's chopping up the AC waveform (at the full input voltage) into discrete smaller chunks in time starting from the sine zero crossing. The chopped-up AC waveform is not going to work well with your step-up microwave transformer, which is why it's not working at all until you turn it all the way up and the power control module starts outputting the full ac waveform.
Thank you a lot for the explanation! That makes sense and other comments agree with you.
It's a bit disappointing, that there is no small option that fits I side the housing of the power supply. Smaller variacs seem to be very expensive.
Looks amazing
Thank you!
Great video, Thank you.
Your PSU voltmeter is probably reading about 20% high at full output voltage because your big resister will have a VCR (Voltage coefficient of resistance) of about -200PPM/volt (maybe more) meaning its resistance will be about 20% lower than marked at 1000V.
The easiest solution to this issue is to put several resistors in series so that each sees a lower voltage, for example using 10 resistors with 100V across each would reduce your resistance drift to 2% which is similar to the analogue meter accuracy.
I am not sure of alloy used but I have seen many stainless steel pots which are magnetic and stores use a small magenta to prove it will work with induction stoves.
A magnetron has negative resistance. But it is not an inductive load. Simple current control works fine. As does power control.
I really enjoy sputtering videos, so this was great!
Hi! The best solution is avoid electronics and use a variac to control the input voltage.
Should condensation continue to be a problem, you might circulate air via a small diameter tube, perhaps fenestrated, run alonside the wires and other tubes
A good idea! But I think I will first try do not use cooling water below room temperature, since It's not necessary. That should hopefully solve the issue.
Das Problem mit dem "power Controller" ist das ist im Prinzip ein PhasenANschnittsdimmer. (Triac, billig, alte Technik)
Das heißt der schaltet die Sinuswelle erst ab einer gewissen Spannung ein.
Wenn der Trafo nicht stark genug belastet ist schießt der einfach nach oben wo die Spitze der Sinuswelle ist und gibt Spannung ab. Erst wenn er genug gesättigt ist reicht die Leistung der abgehackten Sinuskurve nicht mehr aus die Spannung am Ausgang hoch zu treiben! (magnetische impendanz)
Um die Spannung quasi im Leerlauf gut zu regeln brauchst du warscheinlich einen PhasenABschnittdimmer, die funktionieren mit Feldeffekttransistoren und schalten ab einer gewissen Spannung der Welle ab.
Bin mir aber nicht sicher ob das schlagartige abschalten nicht auch hohe Spitzen verursacht, ist aber mit nem minimalen Balstwiderstand bestimmt hinzubekommen.
Der Variac ist aber warscheinlich die geschmeidigste Lösung! 😄
Vielen Dank für diese sehr hilfreiche Erklärung! Ich denke ich werde vorerst bei dem Stelltransformer bleiben. Eventuell teste ich bei Gelegenheit mal einen Phasenabschnittdimmer.
Es gibt genug Labornetzteile die einen Phasenanschnitt Dimmer auf der Primärseite des Trafos als Vorregler benutzen, das funktioniert ohne Probleme.
Dafür muss der Triac aber korrekt angesteuert werden, das geht mit diskreten Komponenten nur recht aufwändig.
Erzeugt man die Zündimpulse elektronisch kann man auch induktive Lasten sinnvoll regeln.
@@AdvancedTinkering Phasenabschnitt ist keine gute Idee in Verbindung mit induktiven Lasten. Versucht man den Stromfluss zu unterbrechen quittiert das die Induktivität mit einem erhöhen der Spannung bis der "Schalter" durchschlägt. Bei elektronischen Schalten also eine mehr oder weniger schnelle Zerstörung.
Phasenanschnitt ist schon das richtige wenn man Transformatoren steuern will.
Aber es muss eben richtig gemacht werden. Ich habe sehr gute Erfahrungen damit gemacht Triacs mit einem Microcontroller anzusteuern.
Muss man eben den Nulldurchgang der Spannung erkennen und einen Timer im Controller darauf synchronisieren.
Damit kann man denn den Triac zum passenden Zeitpunkt zünden. Das geht recht feinfühlig und es wäre auch denkbar eine Rückkopplung einzubauen so dass man die abgegebene Spannung misst und somit konstant hält.
Look at videos about spot welders made from MOT's to see arduino circuits etc to control the voltage etc in your power supply transformer.
You could try* to put an iunno.... 100nf? capacitor across the power controls output.. it might trick it into "working" but a triac isnt a good way to run a transformer.
inverter microwave power supplies have pwm control of the output voltage and safety features that insure u cant power it on at full power and that there isnt a short built into a module that's lighter and smaller then a traditional mot
I will take a look into that. Thanks!
@@AdvancedTinkering yea there are videos on youtube about how to get them working but they arent very high quality. they tldr is that there is a 4 wire harness connected to the board besides the mains ac inputs. the wires r vcc(5volts) , gnd, pwm input(220hz i think?), and some feedback signal that u need to pull to ground with 10k resistor.the pwm to be less then ~30-40% duty cycle to turn it on then can be increased. theres a video of a guy who builds a 555 based solution and a different guy used an arduino but i just got a lcd pwm module that made it easy
Why don't you make the bottom PTFE tubes longer, extending out of the bottom plate long enough to prevent arcing?
My heart dies when I hear someone using a mill in a hand drill, but if it works it works…
Not quite a proper die grinder, but if it removes metal is a satisfactory way and dosen't kill the tool...
I have been known to make ad-hoc lathes from hand drills, angle iron and a prayer. Welded a hole in a tank with a bottle pf propane, someones grandpas oxygen tank, and some tubing and coathangars. If it needs done now, you can do it now, but usually not correctly. If only temporary fixes weren't the most permanent.
You might have the wrong resistance value for the potentiometer. If you used a 10K ohm vs. a 100K ohm the curve of the output of the controller would be more linear
Is there a reason why those screws with the PTFE insulators need to be metal? Could they not be swapped out for PTFE screws (or even ceramic, but those are expensive and hard to get...)
Using plastic Screws (PTFE or PEEK) was my first approach but they are so expensive. Especially when they are not "standard size".
Nylon screws are more affordable but it's not a good material for vacuum applications and I could not find the size I need.
@@AdvancedTinkering Ahh, fair enough. I hadn't realised how expensive PTFE screws were!
What if you put the screws connecting the HV section to the base into some ptfe inserts in the holes in the HV block? If you make them expand into the holes like a hollow wall molly or an expanding concrete anchor. Then you would not need a metal to metal connection there.
At 6:09 you talk about the screw isolation. Why don't you get teflon rod and chop fitting plugs that go onto the screw heads? Cheap DIY-plugs shouldn't be too expensive to replace, even if every removal is destructive. You might get it working with teflon tubing as well.
That or have the pfte inserts extend a cm or so above the ground potential part. If you’re building your own based of the CAD files you can just extrude the ‘pipe’ section of the existing model a bit:)
Makes me wonder if electroplating corrosion-prone surfaces could be a viable solution
Can't you just make longer PTFE insulators in order to increase the creepage distance? Since they would protrude from the bottom, it shouldn't matter if they had a longer shoulder that sticks out from the magnetron.
inches - is that a unit?, how many saarlands or soccer fields is that again? 🙃
It's 0.167 foot. If that helps ;)
Football field you mean
@@AdvancedTinkering ok as a tinkerer your allowed to use freedom units, i guess 😜 #engineer-upgrade
@@AdvancedTinkering Whose foot?
@@R.Daneel Mine, but only until the second mangled toe.
Coat the iron plate with vacuum-rated epoxy.
Fantastic, really well done. Can you or maybe someone in the comments send me specs/details on your power controller? I can't promise you anything other than I am not a time waster and it will bug the life out of me until its resolved, lol, I do love problem solving. Peace and best wishes from Ireland., take care mo chara.
hi, thanks for the video!
I was wondering if it is possible to get CAD files of your design?
Very nice but no link to Patreon
Can you gold-plate condenser microphone diaphragm with this ?
Damn.. 1000 bucks for these simple parts.. Having a lathe you can do all this work.. If people needed all this more often, workshops would get rich
Considering that this is made in China, it would cost more in the USA.. Although you would only need a dividing device and a drilling machine, everything else is done on a lathe, especially the fluoroplastic bushings
tasting antifreeze is really something
Dose makes the poison, not merely the substance
@@custos3249 yummers
What about using copper o-rings?
Can’t you use Nylon or Glasfiber Screws to prevent arcing
What’s the Benefit of putting the Magnetron into the Vacuum Chamber compared to feeding via a WaveGuide?
Can the desired Field only be created on Top of the Magnetron?
what if you use the magnetron itself to coat the magnetic steel part with nickel
what are the costs and timewaste of constructing such machine.......would it not better to buy one from professionals or let the sputter
If the water is pumped directly into the cathode, how does it not carry high voltage with it? Is it dangerous?
The water should be distilled water and the hoses meed to be long enough. Then the resistance is high enough and it's not a problem.
@@AdvancedTinkering I was doubt it, thank you!
Voltage controller doesn't like inductive loads? Comments?
I guess the teflon sleeves are so expensive because of the thin wall thicknesses?! Other than that they don't look very special?! .. hmm, ich weiß nicht.. außer scharfe Werkzeuge scheint man dafür nichts exotisches zu brauchen?
You do know this magnetron could make you some good cash... I am thinking you could do aluminum coatings for optics,
Ah sputtering
I am Numero Dos and not Numero Uno!
What are you doing with that? Bet you can make a bag of popcorn pretty fast
There's lots of seals in this design...
Talk more mixed units of measure to me you dirty boy; gorgeous design, FAR from amateur-you are too humble!
Россия и Украина - Братья! Привет от Новосибирска!
It is not entirely clear why it was impossible to use a magnetron from a microwave oven. It would be cheaper and easier.
It's not the same as a magnetron in a microwave. But it's still called magnetron. You can look it up in the article/review I cited under the picture I have used. doi.org/10.1016/S0042-207X(99)00189-X
But I understand the confusion. I am not sure where the name comes from.
@@AdvancedTinkering I figured it out. A conventional magnetron is quite applicable, but additional equipment is required, in the form of an ion cannon, and related equipment. The magnetron you use combines these two things in itself.
I thought it was a piston
Are you sure this device should be called Magnetron?
Well, that's what it's called ;)
I can make you all the components for less.
one electrode is connected to the magnetron what is the other electrode connected to?
so the magnets contain the electrons & force it through the center.
why use cooling water & not a refrigerent?
The power circuits and other technologies you're working with are too far outside my knowledge for me to contribute anything useful, but I do want to acknowledge the types of comments popping up for this video. Not only is your channel fascinating to watch (and you clearly know your stuff, as well as being a great presenter) but there are hundreds of people who genuinely seem to know what they're talking about chiming in and discussing what should be an extremely niche, nerdy topic.
Next time anyone despairs over the state of the world and has the "oh god people are so stupid these days we're doomed" thoughts, just remember there are hundreds of people discussing high vacuum equipment, the best controllers for inductive loads and solutions to galvanic corrosion.
There are some interesting people out there doing some pretty awesome things, and it's pretty cool that we get to stumble upon this stuff with a few minutes and an internet connection, not that long ago all this stuff was hidden away in universities and engineering teams