A multi-beamlet injector for heavy ion fusion: Experiments and modeling

Abstract

.We have performed experiments and modeling to evaluate a proposed merging beamlet approach for use in a compact high-brightness Heavy Ion Fusion injector. We used an RF plasma source to produce the initial beamlets. An extraction current density of 100 mA/cm 2 was achieved, and the thermal temperature of the ions was below 1 eV. An array of converging beamlets was used to produce a beam with the envelope radius, convergence, and ellipticity matched to an electrostatic quadrupole channel. Experimental results were in good quantitative agreement with computer simulations and have demonstrated the feasibility of this concept. The size of a driver-scale injector system using this approach will be several times smaller than one designed using traditional single large-aperture beams. The success of this experiment has possible significant economical and technical impacts on the architecture of HIF drivers.

Research and development toward heavy ion driven inertial fusion energy

“…Since then, HIF R&D has demonstrated the production of single ion beams with the required emittance, current, and energy, suitable for injection into an induction linac [36,37]. The repetition rate for these sources was low, and the total operating hours and the number of extracted pulses were still well below the number of pulses required in a driver in 1 yr at $10 Hz.…”

“…Beams 16, 024701 (2013) 024701-5 the extraction process. Such an injector (for argon ions) was tested (and shown to extrapolate well to xenon for a driver) [37,39,40]. For a multiple-beam accelerator and target physics facility, R&D demonstrating at least one design for a multiple-beam injector is a prerequisite.…”

“…A physics design of the injector would be explored through advanced modeling of the beam and any background beam gas and halo-produced secondary electrons. The designs would first be verified on a test stand equivalent to the STS-500 [37] (a 500-kV ion source test stand furnishing flat high voltage (HV) pulses of up to 20-s duration) with one beam, to be followed by a multiplebeam test stand.…”