Recent content by meekg

We didn't think of that. If we can't hit the main modes, we can always weigh it down. Thanks.

ah.

yes - that's my thinking too. (Mine was a WAG - what does the S stand for?)

is it amorphous? (out of curiosity... we're not changing the material to glass right now... machining too complex, too late..)

Storage is -20C to 80C - nothing crasy. Forces are light. I'm worried about internal stresses. We'll be gping through several heat treatment cycles and other tricks. Since internal stresses are a function of (also) microstructure, choice of alloy can be important.

The fabrication tolerance is much looser than that. After fabrication, the piece is measured, and other calibration is performed. However, material creep in excess of 0.5um will take the instrument out of alignment. Ti was chosen for other reasons, among them strength-to-weight and non-magnetism.

I'm looking to choose a Ti alloy for a reference structure for a physics experiment. The structure is about 15"x6"x6" and is relatively heavily gutted by machining. The reference surfaces should not move more than 0.5um during 1 year. Temperature will be stable. We will heat treat as much as...

my omission. The target base pressure is 1E-7 Torr. The concern is about the total quantity absorbed in the walls (as opposed to the outgassing rate), since after initial pump-down to 1E-3 torr, only a getter is available to pump it down to and maintain to 1E-7 torr. I guess the question was...

Anyone familiar with best practices for finishing Ti surfaces for a UHV enclosure? Mechanical polishing to what level? any chemical or electro-chemical processes?

Has to be non-magnetic. A hot-cathode gauge can be added, though will probably break on launch. (but will work during storage)

ok - so I undrstand the the issue is not leak rate, but success (or failure) rates. With high volume applications, if there's a certain chance of the procedure not sealing, it translates directly into yield numbers. For this design, if the procedure fails, the experiment won't work, so it...

I have a chamber that houses a getter pump and nothing else. The chamber is closed with a gate valve and a pinch-off tube. I plan to pump it down, activate the getter, seal the gate valve, and then look for leaks using an RGA. When satisfied, I'll close the pinch-off, and the whole assembly...

I'm looking for numbers on leak rates using pinch-off tubes. Thanks, Ben.

I'm building a mechanism that should be compatible with a 1E-7 Torr environment. (The chamber is sealed, and is pumped by a Getter) There are a number of parts (e.g. a 4mm diameter by 15mm long push-rod, an M4 nut and washer) that need to be insulating. I'm looking for a few good materials...

I meant Beryllium... :)