Magnetically Collimated Energy Transport by Laser Generated Relativistic Electrons

Key, M H

Lawrence Livermore National Laboratory

关键词: Thermonuclear Reactors;    Magnetic Fields;    Collimators;    70 Plasma Physics And Fusion Technology;    Electron Beams;   

DOI  :  10.2172/15013544
RP-ID  :  UCRL-ID-142488
RP-ID  :  W-7405-ENG-48
RP-ID  :  15013544

美国|英语

来源: UNT Digital Library

【 摘 要 】

The possibility of fast ignition of thermo-nuclear fusion is stimulating research interest and activity worldwide. Fast ignition (FI) offers significantly higher gain than conventional spark ignition and the high gain opens the way to an efficient fusion energy producing cycle with laser drivers. The key to FI is the efficient transport of energy from a short pulse laser beam, the igniter, to a small ignition spark in compressed deuterium-tritium fuel. The primary candidate process enabling such energy transfer, is the absorption of laser light and its conversion into a beam of relativistic electrons, which heats the spark. Theory has predicted self-induced magnetic collimation of the electron beam, which could enable efficient transport from the absorption point to the ignition spark. Experiments are required to understand this highly complex process which involves currents in the electron beam, which greatly exceed the Alfven current limit6 (at which the Larmor radius of an electron in the magnetic field associated with by the current is smaller than the radius of the beam). Almost complete current compensation by cold electron return current is therefore required. The oppositely directed hot and cold electron flows initiate strong growth of the Weibel instability, which causes the currents to break up into microscopic filaments. The net forward current at less than the Alfven limit however generates a magnetic field, which acts to collimate the overall electron flow.