Recent US advances in ion-beam-driven high energy density physics and heavy ion fusion

Abstract

During the past two years, significant experimental and theoretical progress has been made in the U.S. heavy ion fusion science program in longitudinal beam compression, ion-beam-driven warm dense matter, beam acceleration, high brightness beam transport, and advanced theory and numerical simulations. Innovations in longitudinal compression of intense ion beams by > 50 X propagating through background plasma enable initial beam target experiments in warm dense matter to begin within the next two years. We are assessing how these new techniques might apply to heavy ion fusion drivers for inertial fusion energy. IntroductionA coordinated heavy ion fusion science program by the Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and Princeton Plasma Physics Laboratory (the HeavyIon Fusion Science Virtual National Laboratory), together with collaborators at Voss Scientific and Sandia National Laboratories, pursues research on compressing heavy ion beams towards the high intensities required for creating high energy density matter and fusion energy. In previous research, experiments [1] and simulations [2] showed >100X increases in focused beam intensities in the Neutralized Transport Experiment by transverse compression of an intense ion beam propagating through a background plasma to neutralize >90% of the beam space charge. Section 2 describes recent work on longitudinal compression of an intense beam within neutralizing plasma, and in Sec. 3 we describe studies of initial warm dense matter target experiments that can begin in 2008 after transverse and longitudinal beam compression are combined. Progress in testing a novel Pulse Line Ion Accelerator (PLIA) is described in Sec. 4, e-cloud experiments, theory and simulations in Sec 5, advanced injectors in Sec 6, and advanced theory and simulation models in Sec 7. Section 8 discusses potential applications to heavy ion fusion drivers, and conclusions are given in Sec. 9.

Generalized Courant–Snyder theory and Kapchinskij–Vladimirskij distribution for high-intensity beams in a coupled transverse focusing lattice

“…In practical accelerators and beam transport systems, the transverse coupling between the horizontal and vertical directions, induced by error fields and misalignment, is always a significant effect [3][4][5][6][7][8]. Strong coupling of the transverse dynamics is introduced intentionally in certain type of cooling channels and in the final focusing system for high energy density physics experiment [9], as well as in the conceptual design of the Möbius accelerator [10]. A beam transport system with strong coupling was implemented in the Spiral Line Induction Accelerator (SLIA) [11][12][13][14][15][16][17], which reached up to 10kA electron current at 5MeV beam energy.…”

Generalized Kapchinskij-Vladimirskij Distribution and Envelope Equation for High-Intensity Beams in a Coupled Transverse Focusing Lattice

“…In practical accelerators and beam transport systems, the transverse coupling between the horizontal and vertical directions, induced by error fields and misalignments, is always a significant effect [3][4][5][6][7][8]. Strong coupling of the transverse dynamics is introduced intentionally in certain type of cooling channels [9] and in the final focusing system for high energy density physics experiment [10], as well as in the conceptual design of the Möbius accelerator [11].…”

Theory and simulation of warm dense matter targets

“…The conclusions we draw however are not limited to the NDCX II facility. These high current, low energy beams may require compression and focusing in a neutralized plasma to overcome beam space charge, and plans and experiments for this approach are described in refs [1,[5][6][7][8][9][10][11].…”

“…Typically, the entrance and exit energy (E entrance and E exit ) are chosen to be 1.5 times and 0.5 times, respectively, the energy of the peak in dE/dX. Rearranging equation (1) and putting in values for lithium yields:…”

“…These targets are thus roughly cylindrical in geometry. Recently a collaboration of researchers [1] at LBNL, LLNL, and PPPL (the Heavy Ion Fusion Science Virtual National Laboratory HIFS VNL) has been exploring the possibility of using ions at lower energy (less than 1 MeV per nucleon) but with shorter pulse (~1 ns) and higher current (~100 A). The lower energy implies a very short range (~ 1 to 100 µ) , much smaller than the radius of the focal spot (~1 mm).…”