INVESTIGATION OF SPACE-CHARGE-COMPENSATED ION-BEAMS WITH A TIME-RESOLVING ION ENERGY SPECTROMETER

High perveance ion beams are required for heavy-ion inertial fusion dr ivers. The current limit of a low energy beam transport line is enhanc ed by space-charge compensation. It rise time is several hundreds of m icroseconds under the supposition that electrons are produced by resid ual gas ionization only. Therefore the rise time depends on the residu al gas pressure and ionization cross-section. This is of special inter est for pulsed ion beams, with a pulse length close to or below that r ange. To study this compensation process, we developed a time-resolvin g residual gas ion energy spectrometer with single-particle detection; the available time resolution is about 2 mu s. Experimental results a re presented and compared with a theoretical prediction.