A low energy ion beam system for thermal evolution measurements of damage in ion bombarded single crystals

The use of thermal evolution mass spectrometry in conjunction with the helium probe represents a powerful method of studying the gas-defect interaction processes associated with ion bombardment of single crystal targets. The energy and fluence dependence of the damage build-up processes together with the annealing characteristics of the damage are of considerable importance in view of the widespread use of low energy ion beam and plasma cleaning techniques. The apparatus described comprises a low energy ion gun based on an electron bombardment source and Wien filter and target chamber incorporating a multiple target holder assembly. The design considerations and operating characteristics of the overall system are described and the often used ion bombardment cleaning procedures discussed with reference to experimental thermal evolution measurements of low energy argon and helium trapping.