LLNL, Livermore, California, USA
LBNL, Berkeley, California, USA
PPPL, Princeton, New Jersey, USA
UMD, College Park, Maryland, USA
Intense heavy-ion beams have long been considered a promising driver option for inertial-fusion energy production. This paper briefly compares inertial confinement fusion (ICF) to the more-familiar magnetic- confinement approach and presents some advantages of using beams of heavy ions to drive ICF instead of lasers. Key design choices in heavy-ion fusion (HIF) facilities are discussed, particularly the type of accelerator. We then review experiments carried out at Lawrence Berkeley National Laboratory (LBNL) over the past thirty years to understand various aspects of HIF driver physics. A brief review follows of present HIF research in the US and abroad, focusing on a new facility, NDCX-II, being built at LBNL to study the physics of warm dense matter heated by ions, as well as aspects of HIF target physics. Future research directions are briefly summarized.
LBNL, Berkeley, California, USA
LLNL, Livermore, California, USA
A 130 keV injector is developed for the NDCX-II facility. It consists of a 10.9 cm diameter lithium doped alumina-silicate ion source heated to ~1300 °C and 3 electrodes. Other components include a segmented Rogowski coil for current and beam position monitoring, a gate valve, pumping ports, a focusing solenoid, a steering coil and space for inspection and maintenance access. Significant design challenges including managing the 3-4 kW of power dissipation from the source heater, temperature uniformity across the emitter surface, quick access for frequent ion source replacement, mechanical alignment with tight tolerance, and structural stabilization of the cantilevered 27” OD graded HV ceramic column. The injector fabrication is scheduled to complete by May 2011, and assembly and installation is scheduled to complete by the beginning of July.
PPPL, Princeton, New Jersey, USA
LLNL, Livermore, California, USA
Columbia University, New York, USA
Neutralized drift compression offers an effective means for particle beam focusing and current amplification. In neutralized drift compression, a linear longitudinal velocity tilt is applied to the beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam intensity can increase more than a factor of 100 in the longitudinal direction. We have performed an analytical study of how errors in the velocity tilt acquired by the beam in the induction bunching module limits the maximum longitudinal compression. It is found in general that the compression ratio is determined by the relative errors in the velocity tilt. That is, one-percent errors may limit the compression to a factor of one hundred. However, part of pulse where the errors are small may compress to much higher values determined by the initial thermal spread of the beam pulse. Examples of slowly varying and rapidly varying errors compared to the beam pulse duration are studied.