The diagnostics system for the multiple heavy ion beams induction linac experiment, MBE-4

Abstract

MBE‐4 is a four beam current amplifying induction linac experiment conducted at LBL as a part of the Heavy Ion Fusion Accelerator Research (HIFAR) program for studying accelerator physics issues of a heavy ion driver for inertial fusion. The four ion beams (Cs+, 10 mA) are focused by electrostatic quadrupoles and accelerated from about 200 keV to 900 keV through 24 induction gaps. Current amplification of up to nine times is achieved while the beam pulse duration is compressed from about 3 μs to 0.5 μs. The diagnostic system enables the complete time‐resolved 2‐D transverse phase space distribution of the beam to be measured. Reduction of the raw data yields the beam current, current profile, emittance, centroid position and angle as well as the beam envelope parameters. In addition, the longitudinal energy distribution is obtained from measurements using a calibrated electrostatic spectrometer. The diagnostic system hardware, as well as the data acquisition and reduction routines, are controlled by an IBM pc‐XT. We shall describe the diagnostic system and discuss its performance in view of the specific issues which result from the acceleration and amplification of multiple beams of heavy ions.