MIZUNO REPLICATION AND MATERIALS ONLY

Quote from magicsound

Prototype half-scale cell 40 x 300 mm. The heater is a 150 watt cartridge inserted in the thermowell. I'll initially assemble it without Ni mesh, for vacuum testing and bake out. The ports are both 3/8" Swagelok, welded to the end caps.

Looks good and very well made. Several questions: What size Conflat flanges are those? Also, the Conflat nipple looks longer than the standard size. Did you have one custom fabricated? Is the sheath heater secured via a Swagelok ferrule or is the long interior tube a closed end affair into which the sheath heater is inserted?

Quote from jeff

Looks good and very well made. Several questions: What size Conflat flanges are those?

Yes, looks nice. Where did you get the conflat?

Quote from Curbina

streamed as a live experiment?

Yes, probably streamed. The initial testing and calibration may not be streamed live, but the data will be posted as near to real time as possible.

Here is another thought to help determine the importance of heat vs. IR radiation of the mesh.

Use a solid state relay to pulse the power to the heater and/or Halogen bulb. Run it at constant power, say 100W and measure the heat output. Then pulse it at 1000W 10% duty cycle (maybe 100ms on, 900 ms off) and measure heat. The thermal time constant should make the mesh temperature nearly equal in both cases, but the 10x pulses of IR (and probable nonlinear response) may make the heat output of the pulsed version higher.

I would suggest a zero-crossing SSR to reduce noise to the other electronics. These switch only at the zero crossing of the AC input and do not introduce noise from switching high currents. You might use something like this one and drive the control from a signal generator:

https://www.digikey.com/produc…SR-240D25/PB545-ND/678179

Does anyone have the exact model of the outlet fan?

I see it is a Servo brand, but cannot make out the part number, voltage or rated current from the photos. The 2017 paper image Figure 14 is the best image so far. That paper describes 12V 0.42A supply to the fan, and that seems to be what I can barely read from the label. However I would like to match the enclosure also.

Quote from magicsound

Prototype half-scale cell 40 x 300 mm. The heater is a 150 watt cartridge inserted in the thermowell. I'll initially assemble it without Ni mesh, for vacuum testing and bake out. The ports are both 3/8" Swagelok, welded to the end caps.

Are any of these welding kits on Amazon suitable for these vacuum tight welds?

https://www.amazon.com/Forney-…64949001&s=gateway&sr=8-3 (flux core, gasless)

(potentially messy:

This one is only $100, requires your own oxygen and acetyline gas bottles I believe:

https://www.amazon.com/ZENSTYL…64949495&s=gateway&sr=8-4

Zeny Arc welder $118:

https://www.amazon.com/ZENY-We…64949802&s=gateway&sr=8-3

I have a 6" conflat blank on the way, I'm thinking about drilling two holes into and welding gas and heater to it.

Welding SS316 is pretty tricky. For vacuum systems, I think only TIG welding will give acceptable results. The welding shop I used has a turntable system, so the flange-to-tube welds are continuous and smooth around the joint.

With all due respect to my friends Alan and Alan above, according to my TIG instructor and my own personal experience, TIG welding stainless is relatively easy compared to mild steel, and far easier than aluminum. Note I said "relatively".

TIG is by far the best welding method for this use as compared to wire feed, stick or gas. There may be better methods beyond the financial means of small shop welding, but I don't know about them. Disclaimer: I haven't welded pressure/vacuum vessels. (but I suspect it's in my near future...)

(Edit: OK I have, but that was rough, overbuilt and explosion proof, not precision work)

The key (as always) is cleanliness. TIG is inherently clean but never use the same cleaning tools (wire brushes, wipes etc) with any other materials. Keep Acetone handy and keep your filler rod pristine. Never let anything that will touch the weld area touch anything else after cleaning.

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Regarding welding of SS: TIG welding is the preferred method. I had an exhaust system for a homebuilt aircraft fabricated of .040" wall thickness SS tube, and the results were really good. One word of caution: the welder stated that back purging is necessary to prevent oxidation on the reverse side.

Depending on how the cell is constructed, it may be possible to purchase all the needed components pre-welded. For example, LDS Vacuum will fabricate custom length Conflat nipples. End flanges with the appropriate connections are available off the shelf. These include either VCR or Swagelok fittings. Take a look at their website for more details.

I'm finding that the vacuum plumbing is the most difficult thing to learn and design because there are so many choices. Hard metal/hard metal connections and valves, hard metal/soft metal, bellows, etc.

I was planning on using some NPT 1/4" fittings with teflon tape. Is this a bad idea?

My chamber is UHV compatible and bakeable, but my NPT plumbing is not really. However, if I have long copper tubing between my chamber and the rest of the plumbing, like the Deneum setup, then the teflon tape and KF connections should not be subjected to the bakeout temperatures...

Currently I plan on going down to just 0.05 Pa to 0.1 Pa (I'm guessing that's what the used pump will be capable of) with a 2 stage rotary vane pump.

Ditto. Defo not the teflon tape. That's asking for leaks.

Shane D.

Where did you get the report from? I have searched, in vain thus far, for it.