Compact simulators based on electron beam scaled for heavy ion beam driver in inertial confinement fusion

Abstract

In final beam bunch compression for heavy ion-beam driven inertial confinement fusion, the beam dynamics with theoretical and numerical simulation approaches to investigate the limitation of longitudinal pulse compression is studied in comparison with experimental results. Transport of space-charge-dominated beams with low emittance is crucial issue for application to heavy ion inertial fusion (HIF). <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> However, the detail of beam dynamics is unclear, because the beam parameters are far from the particle beams produced from conventional accelerators. It is important to clear the dynamics for the precise control of high-current beams due to effective fuel pellet implosion. The high current (1~100 kA) heavy ion beams are required in the final stage of the particle accelerator system. A compact simulator with an electron beam was constructed to understand the beam dynamics during the final pulse compression for HIF. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Not only from the view point of the experimental apparatus, but also from the view point of the numerical and theoretical approaches, the simplified and scaled simulators are useful to clear the mechanisms of beam dynamics such as the emittance growth. Using the longitudinal envelope equation, the ratio between the repulsion forces due to the space charge and the emittance was estimated. The numerical simulations were carried out in the parameters of compact electron beam experimental devices. These theoretical and numerical approaches suggested that if the initial temperature is low enough, the compact simulator will be able to simulate the beam dynamics around the stagnation point at the unneutralized bunch compression.