An ion beam for HIF must have high "brightness," that is high current and low emittance temperature, in order to deliver high power onto a small target spot. A first step in achieving this is to begin with the minimum possible emittance at injection.

Present HIF power plant concepts require 5--110 Amperes of beam current arranged in multiple beam channels of about 0.5 Amperes each, with an injection energy of about 1.6 Megavolts. An effective way to do this, which overcomes space charge limits, is to produce these high current beams by merging a large number of high-current beamlets.

To study the emittance growth of beam merging, the LBNL scientists injected 119 beamlets into an electrostatic quadrupole channel. At 400 kV (1/4 full voltage) the beam current obtained was 70 mA, which scales to 0.56 A at 1.6 MV.

For further information, contact Joe Kwan: jwkwan@lbl.gov