skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Plasma Diagnostics of a Forward Laser Plasma Accelerated Thruster

Abstract

Fundamental investigations on plasma diagnostics of a forward laser plasma acceleration employing laser-foil interactions were conducted for an Al-foil target irradiated with an Nd:YAG laser of 1J/pulse with pulse-width of 10nsec. A time-of-flight measurement was also conducted to evaluate ion speeds. In addition, temporal evolutions of electron temperatures and densities were evaluated with electrostatic probes and spectroscopic diagnostics. Moreover, a preliminary one-dimensional particle-in-cell (PIC) simulation was conducted to elucidate acceleration mechanisms. From the results, it was shown that a speed of ions in a forward direction were about 135 km/sec, respectively. Also it was shown that the plasma temperature and density were about 2.5{approx}3 eV and 1010 cm-3.

Authors:
; ;  [1];  [2]
  1. Tokai University, Hiratuka-shi, Kanagawa, 259-1292 (Japan)
  2. University of Tokyo, Bunkyo-ku, Tokyo, 113-8856 (Japan)
Publication Date:
OSTI Identifier:
20800238
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 830; Journal Issue: 1; Conference: 4. international symposium on beamed energy propulsion, Nara (Japan), 15-18 Nov 2005; Other Information: DOI: 10.1063/1.2203263; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ELECTRON TEMPERATURE; ELECTROSTATIC PROBES; EV RANGE; ION TEMPERATURE; IONS; LASERS; PLASMA; PLASMA ACCELERATION; PLASMA DIAGNOSTICS; PLASMA HEATING; PLASMA PRODUCTION; PLASMA SIMULATION; PROPULSION; PULSES; THRUSTERS; TIME-OF-FLIGHT METHOD

Citation Formats

Izumi, Masaya, Horisawa, Hideyuki, Takeda, Akihito, and Kimura, Itsuro. Plasma Diagnostics of a Forward Laser Plasma Accelerated Thruster. United States: N. p., 2006. Web. doi:10.1063/1.2203263.
Izumi, Masaya, Horisawa, Hideyuki, Takeda, Akihito, & Kimura, Itsuro. Plasma Diagnostics of a Forward Laser Plasma Accelerated Thruster. United States. doi:10.1063/1.2203263.
Izumi, Masaya, Horisawa, Hideyuki, Takeda, Akihito, and Kimura, Itsuro. Tue . "Plasma Diagnostics of a Forward Laser Plasma Accelerated Thruster". United States. doi:10.1063/1.2203263.
@article{osti_20800238,
title = {Plasma Diagnostics of a Forward Laser Plasma Accelerated Thruster},
author = {Izumi, Masaya and Horisawa, Hideyuki and Takeda, Akihito and Kimura, Itsuro},
abstractNote = {Fundamental investigations on plasma diagnostics of a forward laser plasma acceleration employing laser-foil interactions were conducted for an Al-foil target irradiated with an Nd:YAG laser of 1J/pulse with pulse-width of 10nsec. A time-of-flight measurement was also conducted to evaluate ion speeds. In addition, temporal evolutions of electron temperatures and densities were evaluated with electrostatic probes and spectroscopic diagnostics. Moreover, a preliminary one-dimensional particle-in-cell (PIC) simulation was conducted to elucidate acceleration mechanisms. From the results, it was shown that a speed of ions in a forward direction were about 135 km/sec, respectively. Also it was shown that the plasma temperature and density were about 2.5{approx}3 eV and 1010 cm-3.},
doi = {10.1063/1.2203263},
journal = {AIP Conference Proceedings},
number = 1,
volume = 830,
place = {United States},
year = {Tue May 02 00:00:00 EDT 2006},
month = {Tue May 02 00:00:00 EDT 2006}
}
  • A fundamental study of a forward laser accelerated plasma thruster was conducted. In order to evaluate thrust performances of the thruster, a time-of-flight measurement was conducted for an Al-foil target irradiated with an Nd:YAG laser of 1J/pulse with pulse-width of 10nsec. From the measurement, the average plasma speed was about 53 km/sec. Time-gated imaging of the plasma with an ICCD camera was also conducted. From the observation, rapid plasmas were observed on both sides of the target. Each image from the ICCD camera was processed by an image processing software into an emission intensity distribution of the plasma at everymore » 10nsec. Axial velocity of the plasma was estimated from the temporal evolution of the plasma edge. The average and maximum plasma expansion velocities in a forward direction were estimated about 40 km/s and 160 km/sec, respectively.« less
  • The maximum energy of protons that are accelerated forward by high-intensity, short-pulse lasers from either the front or rear surfaces of thin metal foils is compared for a large range of laser intensities and pulse durations. In the regime of moderately long laser pulse durations (300-850 fs), and for high laser intensities [(1-6)x10{sup 19} W/cm{sup 2}], rear-surface acceleration is shown experimentally to produce higher energy particles with smaller divergence and a higher efficiency than front-surface acceleration. For similar laser pulse durations but for lower laser intensities (2x10{sup 18} W cm{sup -2}), the same conclusion is reached from direct proton radiographymore » of the electric fields associated with proton acceleration from the rear surface. For shorter (30-100 fs) or longer (1-10 ps) laser pulses, the same predominance of rear-surface acceleration in producing the highest energy protons is suggested by simulations and by comparison of analytical models with measured values. For this purpose, we have revised our previous analytical model of rear-surface acceleration [J. Fuchs et al., Nat. Phys. 2, 48 (2006)] to adapt it to the very short pulse durations. Finally, it appears, for the explored parameters, that rear-surface acceleration is the dominant mechanism.« less
  • An assessment of a novel laser-electric hybrid propulsion system was conducted, in which a laser-induced plasma was induced through laser beam irradiation onto a target and accelerated by electrical means instead of the direct acceleration only by using a laser beam. A fundamental study of newly developed rectangular laser-assisted pulsed-plasma thruster (PPT) was conducted. Inducing a short-duration conductive plasma between electrodes with certain voltages, short-duration switching or a discharge was achieved. At low-voltage conditions ({approx} 100 V), applied to electrodes or charged to a capacitor, it was confirmed that electric discharge can be achieved even under low voltage conditions. Frommore » the results, it was found that discharge duration at the low-voltage case was as long as that of laser-induced plasma. Therefore, the discharge in the low-voltage case must be controlled with an incident laser pulse, or a laser-induced plasma. While in high-voltage cases ({approx} 2000 V), the discharge duration was much longer than that of laser-induced plasma. In this case, the laser-induced plasma should be leading main discharge from a capacitor, where some amount of neutral components of vaporized propellant must be ionized through the discharge. Considering ratios of the laser energy to the discharge energies, the discharge process in the high-voltage mode cases must be defined as the laser-assisted electric discharge, or the laser-assisted electric propulsion mode, while in the low-voltage mode case with smaller electric energy, as the electrically-assisted laser-induced process, or the electric-assisted laser propulsion mode. Moreover, plasma behaviors emitted from each thruster in various cases were observed with the ICCD camera. It was shown that the plasma behaviors were almost identical between low and high voltage cases in initial several hundred nanoseconds, however, plasma emission with longer duration was observed in higher voltage cases. Canted current sheet structures were also observed in the higher voltage cases using a larger capacitor.« less
  • This paper reports on the development of a method for measuring xenon plasma properties using the laser Thomson scattering technique, for application to ion engine system design. The thresholds of photo-ionization of xenon plasma were investigated and the number density of metastable atoms, which are photo-ionized by a probe laser, was measured using laser absorption spectroscopy, for several conditions. The measured threshold energy of the probe laser using a plano-convex lens with a focal length of 200 mm was 150 mJ for a xenon mass flow rate of 20 {mu}g/s and incident microwave power of 6 W; the probe lasermore » energy was therefore set as 80 mJ. Electron number density was found to be (6.2 {+-} 0.4) Multiplication-Sign 10{sup 17} m{sup -3} and electron temperature was found to be 2.2 {+-} 0.4 eV at a xenon mass flow rate of 20 {mu}g/s and incident microwave power of 6 W. The threshold of the probe laser intensity against photo-ionization in a miniature xenon ion thruster is almost constant for various mass flow rates, since the ratio of population of the metastable atoms to the electron number density is little changed.« less
  • The dependences of the observed maximum proton energy on laser fluence, and the type and thickness of the target material were studied. The maximum proton energy depended on the laser fluence rather than on the laser intensity for laser pulses with energies between 40 and 430 mJ and pulse durations between 55 and 400 fs. The maximum proton energy increased as the product of target thickness and target mass density decreased. When a polyimide tape target of 7.5 {mu}m thickness was irradiated, the observed maximum proton energy and flux, counted as the number of etched tracks with a solid anglemore » of 0.25 sr, were 3.3{+-}0.1 MeV and 4x10{sup 6}/MeV/shot, respectively. For efficient proton acceleration when a wide ion emission angle is acceptable, polyimide was suitable for the tape target because it contains much hydrogen, and furthermore, it has a low mass density and a high tensile strength.« less