Heavy-ion fusion accelerator research

The effort at LBL, in terms of Inertial-Confinement Fusion, is concentrated on drivers based on heavy-ion beams (which can be produced reliably and efficiently at high repetition rates) - in particular, on heavy-ion induction linear accelerators. The attractions of this latter concept, in comparison with the heavy-ion rf linacs being studied in West Germany, Japan, and the USSR, are its simplicity, the considerable experience accrued in its application to high-current electron-beam acceleration, and the ease with which it can be extrapolated to large facilities on the basis of experiments with smaller test accelerators. Current plans for exploring the physics and technology of induction linacs involve a series of increasingly sophisticated experiments. The first, which continued to yield results of fundamental significance for our understanding of high-current heavy-ion beams, is the three-year-old single-beam transport experiment (SBTE). Second is the multiple-beam experiment (MBE-4), the apparatus for which is now nearing completion. This experiment is already exploring the physics of four independent beams as they are accelerated and transported through a multigap accelerating structure. Most significantly, the novel feature of current amplification which will be required in a driver has already been demonstrated. Finally, proposed is a much larger Induction Linac System Experiment (ILSE), which would address the main physics and technology issues of a full-size heavy-ion fusion reactor driver, at about a one-tenth scale for many key accelerator parameters