Minimum background plasma density for plasmahyphen;grounded ehyphen;beam targets

摘要

A density criterion is derived for background plasmas intended to carry return current from an ehyphen;beam heated target. The criterion arises due to the depletion of the ions near the target and resultant potential change of the target. It is concluded that plasma densities near the target need to be about 1020cmminus;3for breakeven fusion systems.