Toward a physics design for NDCX-II, an ion accelerator for warm dense matter and HIF target physics studies

Abstract

The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL), a collaboration of LBNL, LLNL, and PPPL, has achieved 60-fold pulse compression of ion beams on the Neutralized Drift Compression eXperiment (NDCX) at LBNL. In NDCX, a ramped voltage pulse from an induction cell imparts a velocity "tilt" to the beam; the beam's tail then catches up with its head in a plasma environment that provides neutralization. The HIFS-VNL's mission is to carry out studies of Warm Dense Matter (WDM) physics using ion beams as the energy source; an emerging thrust is basic target physics for heavy ion-driven Inertial Fusion Energy (IFE). These goals require an improved platform, labeled NDCX-II. Development of NDCX-II at modest cost was recently enabled by the availability of induction cells and associated hardware from the decommissioned Advanced Test Accelerator (ATA) facility at LLNL. Our initial physics design concept accelerates a ∼30 nC pulse of Li + ions to ∼3 MeV, then compresses it to ∼1 ns while focusing it onto a mm-scale spot. It uses the ATA cells themselves (with waveforms shaped by passive circuits) to impart the final velocity tilt; smart pulsers provide small corrections. The ATA accelerated electrons; acceleration of non-relativistic ions involves more complex beam dynamics both transversely and longitudinally. We are using analysis, an interactive one-dimensional kinetic simulation model, and multidimensional Warp-code simulations to develop the NDCX-II accelerator section. Both LSP and Warp codes are being applied to the beam dynamics in the neutralized drift and final focus regions, and the plasma injection process. The status of this effort is described.

Diffuse interface surface tension models in an expanding flow

“…As an example, consider a piece of material that expands under a sudden pulse of energy that comes from laser fusion [21] or heavy ion fusion [12]. The material will breakup, and surface tension plays an important role in the ensuing dynamics.…”

NDCX-II pulsed power system and induction cells

“…Physics designs for the project have been developed using acceleration and compression waveforms produced from a simple circuit model. 6,7 A candidate design is shown in Figure 1 where the voltage waveforms on 34 acceleration gaps are illustrated. …”

A Class Of Generalized Kapchinskij-Vladimirskij Solutions And Associated Envelope Equations For High-intensity Charged Particle Beams

“…Since then, the envelope equations have become a very important theoretical tool for investigating the transverse dynamics of high-intensity beams in uncoupled periodic focusing lattices [1][2][3][7][8][9][10][11][12][13][14][15].…”