A TRANSVERSE PHASE-SPACE MEASUREMENT TECHNIQUE FOR HIGH-BRIGHTNESS, H- BEAMS

A common method of measuring transverse phase-space distributions in charged-particle beams is to intercept the beam with slits, pinhole plates, or wire grids, and to measure the beam distribution after a drift with a parallel-channel collector or a fluorescent screen. Many of the next generation of accelerator applications (e.g., in heavy-ion fusion and transmutation of nuclear waste) will utilize high-beam currents with small phase-space distributions. The power densities of beams will be too large to permit the interception of entire beams. This paper describes a measurement technique that is applicable to H- beams: a small portion of the beam is separated from the full beam by means of photoneutralization with a laser that is upstream from a sweep magnet. Phase-space measurements are made on only the neutralized beam.