NDCX-II project commencing at LBNL
Earlier this year, the U.S. Department of Energy Office of Fusion Energy Sciences approved the NDCX-II project, a second-generation Neutralized Drift Compression eXperiment. NDCX-II is a collaborative effort of scientists and engineers from Lawrence Berkeley National Laboratory (LBNL), Lawrence Livermore National Laboratory (LLNL), and the Princeton Plasma Physics Laboratory (PPPL), in a formal collaboration known as the Virtual National Laboratory for Heavy Ion Fusion Science (HIFS-VNL). Supported by $11 M of funding from the American Recovery and Reinvestment Act, construction at LBNL commenced in July of 2009, with completion anticipated in March of 2012. Applications of this facility will include studies of: the basic physics of the poorly understood 'warm dense matter' regime of temperatures around 1 eV and densities near solid, using uniform, volumetric ion heating of thin foil targets; ion energy coupling into an ablating plasma (such as that which occurs in an inertial fusion target) using beams with time-varying kinetic energy; space-charge-dominated ion beam dynamics; and beam focusing and pulse compression in neutralizing plasma. The machine will complement facilities at GSI in Darmstadt, Germany, but will employ lower ion kinetic energies and commensurately shorter stopping ranges in matter. Much of this research will contribute directly toward the collaboration's ultimate goal of electric power production via heavy-ion beam-driven inertial confinement fusion ('Heavy-Ion Fusion', or HIF). In inertial fusion, a target containing fusion fuel is heated by energetic 'driver' beams, and undergoes a miniature thermonuclear explosion. Currently the largest U.S. research program in inertial confinement is at Livermore's National Ignition Facility (NIF), a multibillion-dollar, stadium-sized laser facility optimized for studying physics issues relevant to nuclear stockpile stewardship. Nonetheless, NIF is expected to establish the fundamental feasibility of fusion ignition on the laboratory scale, and thus advance this approach to fusion energy. Heavy ion accelerators have a number of attributes (such as efficiency, longevity, and use of magnetic fields for final focusing) that make them attractive candidates as Inertial Fusion energy (IFE) drivers As with LBNL's existing NDCX-I, the new machine will produce short ion pulses using the technique of neutralized drift compression. A head-to-tail velocity gradient is imparted to the beam, which then shortens as it drifts in neutralizing plasma that suppresses space-charge forces. NDCX-II will make extensive use of induction cells and other hardware from the decommissioned ATA facility at LLNL. Figure (1) shows the layout of the facility, to be sited in LBNL's Building 58 alongside the existing NDCX-I apparatus. This second-generation facility represents a significant upgrade from the existing NDCX-I. It will be extensible and reconfigurable; in the configuration that has received the most emphasis, each NDCX-II pulse will deliver 30 nC of ions at 3 MeV into a mm-scale spot onto a thin-foil target. Pulse compression to {approx} 1 ns occurs in the accelerator as well as in the drift compression line; the beam is manipulated using suitably tailored voltage waveforms in the accelerating gaps. NDCX-II employs novel beam dynamics. To use the 200 kV Blumlein power supplies from ATA (blue cylinders in the figure), the pulse duration must first be reduced to less than 70 ns. This shortening is accomplished in an initial stage of non-neutral drift compression, downstream of the injector and the first few induction cells. The compression is sufficiently rapid that fewer than ten long-pulse waveform generators are needed, with Blumleins powering the rest of the acceleration. Extensive simulation studies have enabled an attractive physics design; these employ both a new 1-D code (ASP) and the VNL's workhorse 2-D/3-D code Warp. Snapshots from a simulation movie (available online) appear in Fig. 2. Studies on a dedicated test stand are quantifying the performance of the ATA hardware and of pulsed solenoids that will provide transverse beam confinement (ions require much stronger fields than the electrons accelerated by ATA). For more information, see the recent article in the Berkeley Lab News and references therein. Joe Kwan is the NDCX-II project manager and Alex Friedman is the leader for the physics design.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 967743
- Report Number(s):
- LLNL-TR-418583; TRN: US0904561
- Country of Publication:
- United States
- Language:
- English
Similar Records
Toward a physics design for NDCX II, an ion accelerator for warm dense matter and HIF target physics studies
Toward a physics design for NDCX-II, an ion accelerator for warm dense matter and HIF target physics studies
Related Subjects
70 PLASMA PHYSICS AND FUSION
BEAM DYNAMICS
COMPRESSION
CONFINEMENT
ELECTRIC POWER
HEAVY ION ACCELERATORS
HEAVY IONS
INERTIAL CONFINEMENT
ION BEAMS
KINETIC ENERGY
MAGNETIC FIELDS
PHYSICS
PLASMA
POWER SUPPLIES
RESEARCH PROGRAMS
SPACE CHARGE
THERMONUCLEAR EXPLOSIONS
THERMONUCLEAR FUELS
THERMONUCLEAR REACTORS
WAVE FORMS