Nonlinear δf simulation studies of intense charged particle beams with large temperature anisotropy

Abstract

In this paper, a 3D nonlinear perturbative particle simulation code (BEST) [H. Qin, R. C. Davidson, and W. W. Lee, Phys. Rev. ST Accel. Beams 3, 084401 (2000)] is used to systematically study the stability properties of intense non-neutral charged particle beams with large temperature anisotropy (T⊥b≫T∥b). The most unstable modes are identified, and their eigenfrequencies, radial mode structure, and nonlinear dynamics are determined for axisymmetric perturbations with ∂/∂θ=0.

Overview of theory and modeling in the heavy ion fusion virtual national laboratory

“…Examples include: detailed analytical and nonlinear perturbative simulation studies of collective processes, including the electron-ion two-stream instability [2][3][4][5][6][7], and the Harrislike temperature-anisotropy instability driven by T ⊥b T b [8][9][10][11]; development of a selfconsistent theoretical model of charge and current neutralization for intense beam propagation through background plasma in the target chamber [12][13][14][15]; development of a robust theoretical model of beam compression dynamics and nonlinear beam dynamics in the final focus system using a warm-fluid description [16]; development of an improved kinetic description of nonlinear beam dynamics using the Vlasov-Maxwell equations [2,[17][18][19][20], including identification of the class of (stable) beam distributions, and the development of…”

“…Assisted-pinched transport uses a preformed 50-kA channel, created in a gas (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) by a laser and a discharge electrical circuit, to create a frozen magnetic field before the heavy ion beam is injected [43][44][45]. Self-pinched transport uses the ion beam itself to break down a low-pressure gas (1-100 mTorr) [13,46,47], and the net self-magnetic field affords confinement.…”

Thermodynamic bounds on nonlinear electrostatic perturbations in intense charged particle beams

“…One example of the instabilities that occur in these systems is the electrostatic Harris instability [9][10][11][12]15,16 , which is driven by the strong temperature anisotropy (T /T ⊥ 1, where the subscripts and ⊥ denote parallel and perpendicular to the beam propagation) that develops naturally in the frame of an accelerated charged particle beam. Much numerical work has been carried out to characterize this type of instability [9][10][11][12][17][18][19] , and it is therefore of particular importance to develop an analytical framework for comparison with these results.…”

“…Thus, much effort has been devoted to understanding the underlying physics of the nonlinear processes occurring in these beams. An important, tractable approach to solving the detailed dynamics of such systems is often to rely on advanced numerical tools such as particle-in-cell (PIC) simulations [6][7][8] , eigenmode codes 9,10 , and Monte-Carlo codes [11][12][13][14] which can simulate the linear and nonlinear phases of instabilities that may cause a degradation of beam quality.…”

“…Much numerical work has been carried out to characterize this type of instability [9][10][11][12][17][18][19] , and it is therefore of particular importance to develop an analytical framework for comparison with these results. Previous theoretical work has concentrated on investigations of the detailed dynamics of beams with Kapchinskij-Vladimirskij (KV) distributions 20,21 , and two-temperature bi-Maxwellian distributions 11,12 . The formalism presented in here is an important generalization of the Fowler bound 22,23 that fully incorporates effects of the strong self-fields, finite geometry, and nonlinear behavior of intense non-neutral particle beams.…”