Cryosorption Pumping Research Articles

747. The dynamics of cryosorption pumping: S H Bauer and P Jeffers, Cornell University, Ithaca, NY, Oct 1965, NASA-CR-314, 12 pages

747. The dynamics of cryosorption pumping: S H Bauer and P Jeffers, Cornell University, Ithaca, NY, Oct 1965, NASA-CR-314, 12 pages

Cryosorption Pumping of Hydrogen at 20 °K II. Development and Performance of Cryosorption Panels

The development of cryosorption panels consisting of Molecular Sieve adsorbents bonded to refrigerated aluminum plates is described. The sticking coefficient of hydrogen on a cryosorption panel refrigerated with liquid hydrogen was found to be 0.16 in the high-vacuum range, corresponding to a pumping speed of 6600 liter/sec per ft2 of panel. A higher sticking coefficient, near unity, can be obtained with a more efficient shielding of the adsorbent surface against thermal radiation. The pumping speed decreases markedly when the surface is contaminated with more condensable gases, such as nitrogen. Therefore, the cryosorption panels must also be shielded from condensable contaminants. The panels can be mounted directly inside vacuum chambers, and can be scaled up without difficulty.

375. The dynamics of cryosorption pumping: S H Bauer and P Jeffers, J Phys Chem, 69 (10), 1965, 3317–3321

375. The dynamics of cryosorption pumping: S H Bauer and P Jeffers, J Phys Chem, 69 (10), 1965, 3317–3321

233. Dynamics of cryosorption pumping: S H Bauer and P Jeffers,J Phys Chem, 69(10), Oct 1965, 3317–3321

233. Dynamics of cryosorption pumping: S H Bauer and P Jeffers,J Phys Chem, 69(10), Oct 1965, 3317–3321

Quantitative Spark Source Mass Spectrometry Using Cryosorption Pumping.

Quantitative Spark Source Mass Spectrometry Using Cryosorption Pumping.

The Dynamics of Cryosorption Pumping

Dynamic measurements of speed of pumping by activated charcoal cooled to liquid nitrogen temperatures to evaluate cryosorption

Cryosorption Pumping of Hydrogen and Helium at 20 °K

The feasibility of pumping hydrogen and helium gas in large vacuum chambers by adsorption at low temperatures has been investigated. The adsorptive capacity of seven selected adsorbents for hydrogen and helium was determined under equilibrium conditions at temperatures between 20 ° and 40 °K and at pressures from 3×10−8 to 1×10−3 Tort. The adsorptive capacity for hydrogen on coconut charcoal and on several types of molecular sieves at 20 °K was found to be very large. Above 30 °K, adsorptive capacities were found to be too low to be of practical interest. Cryosorption pumping under constant hydrogen gas leak was demonstrated for three of the adsorbents studied: molecular sieves 5A and 13X, and coconut charcoal. However, only the adsorbent surface directly exposed to the gas flow was found to be effective. The capacity and pumping efficiency of this surface were strongly dependent on its temperature. As a result, the adsorbent must be well shielded from radiation, and good thermal contact between the adsorbent bed and the refrigerant must be assured. It is concluded that cryosorption is a promising technique for pumping hydrogen in large space simulation chambers, but cryosorption pumping of helium at 20 °K does not appear practical.

Calculation methods for the design of regenerative cryosorption pumping systems: Milton Manes and R J Grant, trans 10 AVS nat vac symp, MacMillan & Co, 1963, p 122.

Monte Carlo simulations of `order-order' relaxations in AB3 systems with L12 superstructure were carried out assuming vacancy mechanism of atomic jumps with constant atomic pair-interaction energy parameters and the saddle-point energies assigned to jumping atoms. The study was focused on relaxations following an increase of temperature. The simulated long-range order (LRO) relaxation curves fitted weighted sums of two exponentials strongly differing in relaxation times, the longer ones of which obeyed the Arrhenius law. The contribution (weight) of the fast process was gradually reduced when the activation barrier energy for B-atom jumps was increased in relation to that for A-atoms. It was found out that the initial stages of LRO relaxations were dominated by A-atom jumps between different sublattices. In conclusion, it is proposed that the fast component of the disordering relaxations in L12 superstructure is due to highly correlated pairs of A-atom and B-atom jumps, which occur provided the majority B-atoms are sufficiently mobile.