Current Status of the Recirculator Project at Llnl*

The Heavy Ion Fusion Group at Lawrence Livermore National Laboratory has for several years been developing the world’s first circular ion induction accelerator designed to transport space charge dominated beams. Currently, the machine extends to 90 degrees, or 10 half-lattice periods(HLP) with induction cores for acceleration placed on every other HLP. Full current transport with acceptable emittance growth without acceleration has been achieved [1]. Recently, a time stability measurement revealed a 2% energy change with time due to a source heating effect. Correcting for this and conducting steering experiments has ascertained the energy to an accuracy of 0.2%. In addition, the charge centroid is maintained to within 0.6-mm throughout the bend section. Initial studies of matches dependencies on beam quality indicate significant effects. 1 WHY THE RECIRCULATOR Currently, heavy ion beams are being pursued as a candidate for a driver of an Inertial Fusion(IFE) power plant. In such a power plant, ion beams would provide the input energy necessary to ignite small D-T capsules [2]. The accelerator for such a driver would need to accelerate space charge dominated ion beams to a total kinetic energy of a few GeV while providing pulse compression and be able to operate at a rate of ~5-Hz [3,4]. Usually the conceptual design of such a machine is linear, but an alternative concept, which may provide significant cost savings [5], is a circular machine, or recirculator. However, a space charge dominated, ion induction, circular machine has never been built before. Thus, the HIF Group at LLNL has been developing a small recirculator in order to investigate the validity of such a concept.