Cooling of accelerator beams to improve focal properties

For inertial fusion with a heavy ion beam, several storage and buncher rings will be used to accumulate a high-current beam and produce a bunch shape as narrow as approximately 50 ns. The beams extracted from these rings will be transported to the target and used for the implosion of fuels. The key issues among the many accelerator beam dynamics problems are: (1) the suppression of coherent instabilities of high-current, short bunched beams of relatively low energy ( approximately 50 MeV/u); (2) focusing the beam uniformly on the small target through the long beam transport line in the presence of chromatic aberration; and (3) the selection of a structure and materials to achieve a plasma temperature of several hundreds of electron-volts. Present research is focused on beam cooling devices to be installed for the improvement of beam emittance and momentum spread, to assure a small focal spot of the extracted beam on the target. Stochastic and electron beam cooling techniques are being developed.<>