Special Values on cryogenic systems from Janis Research

By: Janis  09-12-2011
Keywords: Cryostat, Sorption Pump,

Delivery: 4 weeks after receipt of order
Warranty: 6 months
Terms: Net 30 days
FOB and shipping points, Wilmington, MA 01887 USA

I. Description

1. He-3 cryostat insert
The He-3 insert includes the following main parts :

  • Inner vacuum can (IVC)
    The inner vacuum can is made of copper in order to keep the vacuum flange on the insert at low temperatures even when the liquid Helium level becomes lower than the IVC flange. The sealing of IVC can is achieved by a greased brass taper seal (shown below).
  • Charcoal sorption pump
    The Charcoal sorption pump (shown below) is located inside the IVC and it is used to reduce the pressure on the top of the condensed liquid He-3 and adsorb all the evaporated He-3 gas when it is kept cold (below 5.0K) by flowing cold He-4 gas/liquid through a stainless steel capillary wound around it. The flow rate can be controlled by a flow meter with a valve at the top of the cryostat. The charcoal sorption pump is also used to release the He-3 gas. The temperature of the charcoal sorption pump is monitored by a Lake Shore silicon diode thermometer.
  • 1K pot
    The 1K pot is used to condense the He-3 gas. A needle valve (V9) is assembled inside the cryostat. It can be controlled from the top of the cryostat in order to adjust the flow rate of helium into the 1K pot. The temperature of the 1K pot is also measured by a Lakeshore model silicon diode thermometer mounted at the bottom.
  • He-3 pot
    The He-3 pot is located at the bottom of the insert. A calibrated Matsushita resistance thermometer and a 25 ohm wire heater are installed on it.
  • He-3 storage vessel and pure He-3 gas
    This insert is designed to take six (6) NTP liter pure He-3. This bargain equipment does not include any He-3 gas, but Janis will work with the customer and apply for He-3 gas from the US Department of Energy (DOE) if the project is funded by the US government.
    The price of He-3 gas with DOE approval is $1,000 per NTP liter.

2. Sample chamber with exchange gas
This He-3 insert can be used in two different ways: sample in vacuum or sample in (He-3) exchange gas.
The sample chamber and the mini-gas handling system are required only if the user needs to cool the sample in exchange gas; they are not required for sample in vacuum operation.

  • Sample chamber
    It is a copper chamber with Be-Cu flange soldered on top of it.
    The Be-Cu flange is indium sealed against the bottom flange of the He-3 pot (shown below).
  • Exchange gas handling system
    The following main parts are included :
    • High pressure bottle and vacuum/pressure compound gauge (G2) (There is no He-3 gas installed for the time being.);
    • Exchange gas evacuation valve (V3) to pump out the sample chamber;
    • Exchange gas directing valve (V4) to direct the exchange gas;
    • φ = 0.049” stainless steel exchange gas filling capillary to the sample chamber; The capillary is thermally anchored at the 1K pot.

Brass Taper Sealed Inner Vacuum Can (IVC)

Charcoal Sorption Pump

Top of the He-3 Insert

He-3 Pot and Sample Chamber

The information in this article was current at 06 Dec 2011

Keywords: Cryostat, Sorption Pump,

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