Articles you may be interested inA highly miniaturized electron and ion energy spectrometer prototype for the rapid analysis of space plasmas Rev. Sci. Instrum. 85, 023305 (2014); 10.1063/1.4865842 High energy electron crystal spectrometer Rev. Sci. Instrum. 80, 076106 (2009); 10.1063/1.3170508 Absolute calibration of an electron spectrometer using high energy electrons produced by the laser-plasma interaction Rev. Sci. Instrum. 79, 083301 (2008); 10.1063/1.2969655 Absolute calibration of image plates for electrons at energy between 100 keV and 4 MeV Rev. Sci. Instrum. 79, 033301 (2008); 10.1063/1.2885045 A high sensitivity electron momentum spectrometer with simultaneous detection in energy and momentum Rev.A high energy electron spectrometer has been designed and tested using imaging plate (IP). The measurable energy range extends from 1 to 100 MeV or even higher. The IP response in this energy range is calibrated using electrons from L-band and S-band LINAC accelerator at energies 11.5, 30, and 100 MeV. The calibration has been extended to 0.2 MeV using an existing data and Monte Carlo simulation Electron Gamma Shower code. The calibration results cover the energy from 0.2 to 100 MeV and show almost a constant sensitivity for electrons over 1 MeV energy. The temperature fading of the IP shows a 40% reduction after 80 min of the data taken at 22.5°C. Since the fading is not significant after this time we set the waiting time to be 80 min. The oblique incidence effect has been studied to show that there is a 1 / cos relation when the incidence angle is .
The development of ultra-intense lasers has facilitated new studies in laboratory astrophysics and high-density nuclear science, including laser fusion. Such research relies on the efficient generation of enormous numbers of high-energy charged particles. For example, laser-matter interactions at petawatt (10(15) W) power levels can create pulses of MeV electrons with current densities as large as 10(12) A cm(-2). However, the divergence of these particle beams usually reduces the current density to a few times 10(6) A cm(-2) at distances of the order of centimetres from the source. The invention of devices that can direct such intense, pulsed energetic beams will revolutionize their applications. Here we report high-conductivity devices consisting of transient plasmas that increase the energy density of MeV electrons generated in laser-matter interactions by more than one order of magnitude. A plasma fibre created on a hollow-cone target guides and collimates electrons in a manner akin to the control of light by an optical fibre and collimator. Such plasma devices hold promise for applications using high energy-density particles and should trigger growth in charged particle optics.
Kalpha x-ray emission, extreme ultraviolet emission, and plasma imaging techniques have been used to diagnose energy transport patterns in copper foils ranging in thickness from 5 to 75 microm for intensities up to 5x10(20) W cm-2. The Kalpha emission and shadowgrams both indicate a larger divergence angle than that reported in the literature at lower intensities [R. Stephens, Phys. Rev. E 69, 066414 (2004)]. Foils 5 microm thick show triple-humped plasma expansion patterns at the back and front surfaces. Hybrid code modeling shows that this can be attributed to an increase in the mean energy of the fast electrons emitted at large radii, which only have sufficient energy to form a plasma in such thin targets.
We report an observation of surface acceleration of fast electrons in intense laser-plasma interactions. When a preformed plasma is presented in front of a solid target with a higher laser intensity, the emission direction of fast electrons is changed to the target surface direction from the laser and specular directions. This feature could be caused by the formation of a strong static magnetic field along the target surface which traps and holds fast electrons on the surface. In our experiment, the increase in the laser intensity due to relativistic self-focusing in plasma plays an important role for the formation. The strength of the magnetic field is calculated from the bent angle of the electrons, resulting in tens of percent of laser magnetic field, which agrees well with a two-dimensional particle-in-cell calculation. The strong surface current explains the high conversion efficiency on the cone-guided fast ignitor experiments.
Freeman, R. R.; Gu, P.; Hatchett, S. P.; Hey, D.; Hill, J.; Key, M. H.; Izawa, Y.; King, J.; Kitagawa, Y.; Kodama, R.; Langdon, A. B.; Lasinski, B. F.; Lei, A.; MacKinnon, A. J.; Patel, P.; Stephens, R.; Tampo, M.; Tanaka, K. A.; Town, R.; Toyama, Y.; Tsutsumi, T.; Wilks, S. C.; Yabuuchi, T.; Zheng, J. Citation Physics of Plasmas.
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