10() 



THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1952 



temperature. The apparatus will accommodate circular surfaces as large 

 as 1| inches diameter. The gases from which ions are derived are ad- 

 mitted through the gas inlet. Thus far experiments have been made 

 with hydrogen, helium, nitrogen and argon. The bombarding voltages 

 have as already noted, been varied from 100 to 30,000 volts and the 

 surface temperatures have been varied from about 20°C to 400°C. The 

 effects of these several variables will be discussed more fully below. 



SAMPLE PREPARATION 



The material to be bombarded is usually prepared in batches of about 

 300 grams in fused silica crucibles roughly cylindrical in shape.- After 

 solidifying, the cast is ground to a cylinder approximately 1^ inches 



TUNGSTEN 

 CATHODE 



GAS 

 NLET 



Fig. 1- 



TO PUMP 



-Bombardment apparatus. 



2Scaff, Theuerer, and Schumacher, A.I.M.M.E., 185, pp. 382-392, 11)4!). 



