Search found 15 matches

by Alexi
Sat Jul 30, 2011 6:47 pm
Forum: Vacuum Technology (& FAQs)
Topic: Calibrated leak as deuterium gas supply.
Replies: 16
Views: 3882

Re: Calibrated leak as deuterium gas supply.

<r>This leak will not work for deuterium. Helium leaks use He diffusion through a glass membrane. Only He has high enough diffusion rates in glass at room temperature.<br/> <br/> Hydrogen diffuses very well through some metals at elevated temperature. We have made a hydrogen filter @work out of a th...
by Alexi
Thu Mar 03, 2011 3:35 am
Forum: FAQs: Vacuum Technology
Topic: #2 FAQ - Mechanical Pump - Diffusion pump?
Replies: 41
Views: 28832

Re: FAQ - Mechanical Pump - Diffusion pump?

Don,

I had encountered similar problem with a little Edwards diff pump. There was a popping sound and no pumping. It happened after mechanical pump oil got sucked into the diff pump. An oil change fixed the problem.

Alex
by Alexi
Sat Jan 15, 2011 10:49 pm
Forum: Vacuum Technology (& FAQs)
Topic: Simple turbo pump controller
Replies: 49
Views: 31359

Re: Simple turbo pump controller

<t>Correct, the pin D is connected to the temperature sensor. When the pump overheats above 50C, resistance between pins D and F drops and the OEM controller shuts down the pump. <br/> <br/> The UGN3077 Hall sensor IC has a built-in voltage regulator and works fine with 4.5V to 24V supply voltage.<b...
by Alexi
Thu Jan 13, 2011 3:04 am
Forum: Vacuum Technology (& FAQs)
Topic: Re: Simple turbo pump controller
Replies: 3
Views: 1672

Re: Simple turbo pump controller

Hi Glenn,

There is new batch of TPH-055 on eBay - Item number: 370474651538.

The homebrew controller will not work with LEYBOLD TURBOVAC 50 85401.

Alex
by Alexi
Mon Jan 10, 2011 1:17 am
Forum: Vacuum Technology (& FAQs)
Topic: Simple turbo pump controller
Replies: 49
Views: 31359

Re: Simple turbo pump controller

Hi Rich,

Yes, the pump gets barely warm after many hours of pumping. However, I left the fan on the pump anyway. The fan seems to be made for 208 or 240V AC. It runs on 120V AC very slowly, but that is enough to keep the pump cold.

Alex
by Alexi
Sun Jan 09, 2011 8:49 pm
Forum: Vacuum Technology (& FAQs)
Topic: Simple turbo pump controller
Replies: 49
Views: 31359

Re: Simple turbo pump controller

<t>Rich,<br/> <br/> There is big difference between the RFP2N08L and RFP2N08 transistors. The L sands for "use with logic level driving sources". The RFP2N08L can provide 2-3 amps drain current at 4V gate voltage and the RFP2N08 - only 0.1-0.3 amps. <br/> <br/> Any transistor, which can provide at l...
by Alexi
Fri Dec 24, 2010 10:30 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Russian neutron detector??
Replies: 4
Views: 2756

Re: Russian neutron detector??

<t>From what little information I could find on the web, this instrument is a three-channel geological gamma spectrometer for measurement of concentrations of K, U and Th (K-P-T) or K, U and Cs (K-P-Ц). <br/> <br/> ПУСК - "start" - starts measurement<br/> ОПРОС - "poll" - selects which one of three ...
by Alexi
Fri Sep 03, 2010 2:47 am
Forum: Vacuum Technology (& FAQs)
Topic: Simple turbo pump controller
Replies: 49
Views: 31359

Re: Simple turbo pump controller

<t>David,<br/> <br/> The pump does "know" how to always start up in the correct rotational direction. Sense of rotation is determined by the phase relationship between the hall sensor signal and the current through the winding. If the hall signal and the current are in phase then the motor spins in ...
by Alexi
Thu Sep 02, 2010 2:09 am
Forum: Vacuum Technology (& FAQs)
Topic: Simple turbo pump controller
Replies: 49
Views: 31359

Simple turbo pump controller

<t>The pump:<br/> <br/> Recently we bought a couple of cheap TPH-055 turbo pumps from eBay (Item number: 370455353773). The motor in TPH-055 is single phase, two poles, permanent magnet; therefore the pump spins at the drive frequency. The winding is center-tapped, which makes it easy to drive it wi...
by Alexi
Thu May 14, 2009 5:14 am
Forum: Ion Gun Design and Construction (& FAQs)
Topic: "STARFIRE" Sesselmann-Hendron Ion Source Published
Replies: 3
Views: 6084

Re: "STARFIRE" Sesselmann-Hendron Ion Source Published

<t>Steven, <br/> <br/> Could you explain how ions get extracted from your ion gun? <br/> I am curious because it looks like almost all positive ions will be attracted to the negative 1000V filament (which is much closer to them then negative grid/reaction chamber), and will be neutralized there.<br/...