Neutral Molecule Desorption from SS(304) and A1(6061) Due to Particle Bombardments
The pressure in both electron and proton storage rings is dependent on the particle wall bombardment molecular desorption rates due in one case (proton storage rings) to ~ keV ions while in the other to ~ 100 eV electrons. Also in order to minimize secondary electron amplification effects in both types of machines the secondary electron emission coefficient should be as low as possible. The above quantities have been measured on A1(6061) and SS(304) materials having had various treatments including a sputter deposition of Ti and TiN in the case of A1. The results indicate for both electron and proton storage rings that SS(304) materials properly prepared have particular advantages over A1 considering both molecular desorption yields and secondary electron emission effects.
Desorption of neutral molecules from Al(6061) by electron and ion bombardment
The desorption of neutral molecules by ion (1000‐eV Ar+) and electron (500 eV) impact on aluminum 6061 surfaces is reported. The molecular desorption yields are determined for the following aluminum treatments: (1) samples prepared with nominally the same laboratory treatments; (2) two types of wet chemistry treatments; (3) various in situ gas exposures (including HC1, C12); (4) glow discharge treatments. In summary, it is found that the various prevacuum treatments have little influence on the desorption yields whereas the in situ Cl2 exposure markedly reduces both the ion and electron desorption yields. In addition, the unit yield energy, E0, is also measured for the above sample conditionings. It is similarly found that neither the prevacuum sample conditionings nor the in situ gas exposures (with the exception of Cl2) affect E0 by more than 10% whereas the in situ Cl2 exposure (1 atm, 10 min) increases E0 by a factor of 2 and provides an example illustrating the possible utility of an in situ chemical...
Secondary Electron Yield vs Primary Energy for Commercial Coated‐Glass Resistance Strips
The mean secondary electron yield has been determined as a function of primary electron energy from 20 to 70 eV for the dynode‐strip surface of a commerical resistance‐strip magnetic electron multiplier. Both the primary energy and the secondary yield were determined by measuring the multiplier output current while varying the voltage applied to the field‐strip input end at each of three fixed dynode‐strip input‐end voltages. The measured mean secondary yield increases linearly from about 1.2 at 20 eV to about 1.7 at 70 eV.