Cryo pumping

Pump-down of the antechamber, following solution experiments, involved sorption pumping and cryo-pumping resulting in the pressure decreasing from ambient to 10 Torr in 5 minutes. The resulting sample surfaces were subsequently examined by both LEFT) and AES after transfer back to the analysis-chamber. 

Tritium is one of the main source terms in accident scenarios for ITER and to meet some of the key requirements for limitation of worker and public dose in accidents, limits need to be placed on the tritium inventory. Due to the ease of mobilization of tritium retained in co-deposited layers (co-deposited films in tokamaks start to decompose, releasing tritium, when exposed to air at temperatures > 520 K, [65-69]), a limit of 350 g is currently set for the in-vessel co-deposition inventory (and 120 g in the cryo-pumps). These limits are set to allow the full release of this inventory, under hypothetical accident conditions, without the need for public evacuation under the worst weather conditions. 

Eichner, Th. (2005) Kryopumpe fur Wasserstoff [Cryo-pump for Hydrogen). Diploma thesis, Technische Universitat Graz. 

The next four lenses, objective, diffraction, intermediate, and projector, are the magnifying lenses. The objective lens is the most important and complex lens in aTEM. The specimen itself is immersed in the lens and is moveable inX, Y, and Z directions, as well as 60° tilt in each direction and rotation through approximately 360°. Since the specimen itself is a major source of contaminants, the objective lens is also fitted with an anticontaminator that functions as a cryo-pump to remove most local contaminants. 

Instrumentation for Capillary SFC-MS. The development of fused silica capillary colusms with stabilized stationary phases suitable for SFC presented the opportunity to eliminate the disadvantages of the molecular beam approach. The typical fluid flow rates for 50 ym i.d. columns are in the range of 1-2 1/min (as liquid) this range can be handled by conventional two stage mass spectrometers (as typically configured with chemical ionization capability) without the use of the liquid nitrogen cryo-pumps required for commercial direct liquid introduction LC-MS interfaces (35). 

Increasing the source housing pump speed, usually with the addition of a cryo-pump. 

To test electric rockets without appreciable interference from the residual gases in the facility, pressures of the order of lO" mm Hg or less must be maintained during operation. To accomplish this with reasonable number of diffusion pumps, it is necessary to provide a condenser inside the vacuum tank to condense the propellant emerging from the thrust unit. This condenser is essentially a cryo-pump. An expression for the amount of surface area required to condense a given mass flow rate was derived by Mickelsen and Childs [15] ... 

Exposures to hydrides (probably a mixture of arsine and phosphine) as high as 60 ppb have been found during ion implanter cryo-pump maintenance. 04] Also, high concentrations of both arsine and phosphine can off-gas from contaminated implanter parts that are removed during preventative maintenance. 0 1... 

In ICP-MS (Fig. 130), the ions formed in the ICP are extracted with the aid of a conical water-cooled sampler into the first vacuum stage, where a pressure of a few mbar is maintained. A supersonic beam is formed and a number of collision processes take place as well as an adiabatic expansion. A fraction is sampled from this beam through the conical skimmer placed a few cm away from the sampler. Behind the skimmer, ion lenses focus the ion beam now entering a vacuum of 10 mbar. This was originally done with the aid of oil diffusion pumps or cryo-pumps, but very quickly all manufacturers switched to turbomolecular pumps backed by roughing pumps. 

Figure 12 Apparatus of the ECR ion beam sputtering system. A, ECR ion gun B, target holder C, rotary pump D, substrate holder E, Kaufman ion gun E, main valve G, cryo pump.

Using an additional getter of cryo-pumping materials, within the vacuum space, as a back-up to the high vacuum needed anyway in the depths of the MLI between the reflectors. 

VF-5 has a diameter of 4 6m (15 ft) and length of 18m (60 ft), and is uniquely suited to test ion thrusters due to its rapid vacuum pump-down speed. With a combination of oil diffusion pumps (ODP) and cryo-pumping, air can be expelled from the chamber at a rate of 3-5 x 10 l/sec. A 10-ton crane is available to handle prototypic components Four test ports with a diameter range of 0.3 to 1.8m (1.0 to 5.9 ft) and length range of 0.3 to 2.4m (1.0 to 7.9 ft) are attached to the chamber. This facility allows for automated, unattended operation. 

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