Neutral beam penetration considerations for CIT

Neutral beam injection into CIT is discussed. Monte Carlo methods are used to evaluate available windows of operating density and beam energies. The beam deposition profile is determined for a wide range of parameters. The effects of the excitation enhanced ionization cross section have been studied, both with and without impurities. Enhanced ionization processes and impurities are found to prevent the penetration of 300 keV deuterium beams. Requirements for low energy beam injection are determined. In order to utilize the TFTR power supplies (300 kV maximum), it is necessary to inject hydrogen beams