J. M. Kindel

University of California, Los Angeles, Los Angeles, California, United States

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Publications (36)119.63 Total impact

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    ABSTRACT: In laser fusion plasmas, most of the absorbed laser energy can go into the generation of suprathermal electrons, which potentially can preheat the pusher and/or fuel. An approach of using a vacuum to shield the pusher or fuel against these energetic electrons is discussed in some detail. Both qualitative and quantitative kinetic calculations governing vacuum insulation in plane and spherical geometry are developed. The principal effect of vacuum insulation is to convert an electron time scale to an ion time scale.
    Nuclear Fusion 01/2011; 19(11):1447. · 2.73 Impact Factor
  • J.M. Kindel, E.L. Lindman
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    ABSTRACT: Target designs using low-energy monoenergetic ion beams with a range of up to several × 10−3 gcm−2 delivering energies of tens of kilojoules to a megajoule have been developed. Minimal pulse shaping produces yield ratios of 10–100. Applications to laser-produced ions show that if the ions are produced from an isothermal expansion, there is a high degree of inefficiency in converting laser energy to useful ion energy in driving an implosion.
    Nuclear Fusion 01/2011; 19(5):597. · 2.73 Impact Factor
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    ABSTRACT: A computational approach for simulations in the emerging field of short-pulse (Τ
    Physics of Fluids B Plasma Physics 08/1991;
  • E.L. Jr. Lindman, J.M. Kindel
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    ABSTRACT: Substantial progress has been made in understanding the operation of plasma opening switches (POS) in support of the Light-Ion Fusion Program at Sandia National Laboratories. Our efforts began with scoping studies using the particle-in-cell (PIC) code, MAGIC, which was written by Bruce Goplen and co-workers at MRC for pulsed-power applications. The version of MAGIC currently at Sandia National Laboratories is supported by Dave Seidel and Tim Pointon. MAGIC continues to play an important role as our studies moved into many different areas. Working closely with Cliff Mendel, we performed initial studies of switches using his fast B/sub z/ concept. Working with Mary Ann Sweeney, Jeff Quintez and Cliff Mendel we performed studies of the effects of plasma density, cylindrical curvature, load impedance, rise time, and emission threshold on switch performance. In addition, we studied B-field penetration, turbulence, anomalous resistivity, and electron heating in plasma opening switches. This work has allowed us to identify the physical mechanisms that are important in the operation of plasma opening switches. Based on our knowledge of the physics we have established scaling relations for comparable switch performance under different experimental conditions. We studied the code requirements for POS simulation and numerical problems in MAGIC and in other PIC codes. And, more recently, we have begun to participate more strongly in the experimental program being carried out on PBFA II. Our conclusions based on these studies are summarized here. 42 refs., 104 figs., 3 tabs.
    01/1989;
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    ABSTRACT: Plasma opening switches have provided a means to improve the characteristics of super-power pulse generators. Recent advances involving plasma control with fast and slow magnetic fields have made these switches more versatile, allowing for improved switch uniformity, triggering, and opening current levels that are set by the level of auxiliary fields. Such switches necessarily involve breaks in the translational symmetry of the transmission line geometry and therefore affect the electron flow characteristics of the line. These symmetry breaks are the result of high electric field regions caused by plasma conductors remaining in the transmission line, ion beams crossing the line, or auxilliary magnetic field regions. Symmetry breaks cause the canonical momentum of the electrons to change, thereby moving them away from the cathode. Additional electrons are pulled from the cathode into the magnetically insulated flow, resulting in an excess of electron flow over that expected for the voltage and line current downstream of the switch. We call these electrons ''launched electrons''. Unless they are recaptured at the cathode or else are fed into the load and used beneficially, they cause a large power loss downstream. This paper will show examples of SuperMite and PBFA II data showing these losses, explain the tools we are using to study them, and discuss the mechanisms we will employ to mitigate the problem. The losses will be reduced primarily by reducing the amount of launched electron flow. 7 refs., 9 figs.
    12/1988
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    ABSTRACT: Described are several new applications of laser-produced plasmas that have arisen in the last few years. Most of the applications have been an outgrowth of the active research in laser/matter interaction inspired by the pursuit of laser fusion. Unusual characteristics of high-intensity laser/matter interaction, such as intense X-ray and particle emission, were noticed early in the field and are now being employed in a significant variety of applications outside the fusion field. Applications range from biology to materials science to pulsed-power control and particle accelerators.
    Unknown. 09/1988;
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    ABSTRACT: The self-focusing of intense electromagnetic waves in a very underdense plasma is studied in computer simulations. Relativistic self-focusing occurs initially. This is followed by ''ponderomotive blowout'' and filamentation at the edge of the channel walls. The self-focusing is more intense for resonant double-frequency than for single-frequency illumination.
    Physical Review Letters 04/1988; 60(13):1298-1301. · 7.73 Impact Factor
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    ABSTRACT: In this paper we report on the recent progress on the Plasma Beat Wave Acceleration Scheme at UCLA as described in a series of talks by the authors at the Symposium on Advanced Accelerator Concepts in Madison. This paper is organized as follows: 1. Introduction 2. Experimental Program 3. Theory Program 4. Simulations Program 5. Summary
    05/1987;
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    ABSTRACT: In the plasma droplet accelerator scheme, proposed by R. Palmer, a sequence of liquid micro-spheres generated by a jet printer are ionized by an incoming intense laser. The hope is that the micro-spheres now acting as conducting balls will allow efficient coupling of the incoming laser radiation into an accelerating mode. Motivated by this we have carried out 2D, particle simulations in order to answer some of the plasma physics questions hitherto unaddressed. In particular we find that at least for laser intensities exceeding vo/c=0.03 (~1013w/cm2 for a CO2 laser), the incident laser light is rather efficiently absorbed in a hot electron distribution. Up to 70% of the incident energy can be absorbed by these electrons which rapidly expand and fill the vacuum space between the microspheres with a low density plasma. These results indicate that it is advisable to stay clear of plasma formation and thus put on an upper limit on the maximum surface fields that can be tolerated in the droplet-accelerator scheme.
    IEEE Transactions on Nuclear Science 11/1985; · 1.22 Impact Factor
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    ABSTRACT: Finite-beam, two-dimensional particle simulations of single- and double-frequency laser-plasma heating are presented. In the single-frequency case, Raman backscatter and side scatter initially heat the plasma. Even in the absence of strong forward Raman scattering, strong subsequent electron heating is observed. When two collinear laser beams with ..delta omega.. = ..omega../sub p/ are used, a coherent plasma wave heats the electrons to many megaelectronvolts. In the latter case, ion dynamics eventually disrupts the heating process.
    Physical Review Letters 03/1985; 54(6):558-561. · 7.73 Impact Factor
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    ABSTRACT: Two-dimensional particle simulations with a finite laser beam show that beat wave acceleration can produce energetic electrons as seen in one-dimensional simulations. The competition and interplay between various nonlinear phenomena -- backward Raman scattering, stimulated Compton scattering, self-focussing, filamentation, and harmonic generation -- were delineated through the two-dimensional simulations.
    Plasma Physics. 06/1984;
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    ABSTRACT: It is shown by theory and by computer simulation that space-charge waves driven by resonantly beating two laser beams in a high-density plasma can produce ultrahigh electric fields that propagate with velocities close to c. By phase-locking particles in such a wave, particles may be accelerated to very high energies within a very short distance. Problems associated with phase-stabilization are discussed, as are the laser and plasma requirements of the technique. Prospects for achieving ultrahigh energies in a new generation of particle accelerators using the technique are briefly addressed.
    Nature 01/1984; 311(5986):525-529. · 38.60 Impact Factor
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    ABSTRACT: Finite laser beam particle simulations of beat wave acceleration show that a coherent plasma wave excited by two-colinear laser beams at a difference frequency equal to the plasma frequency can produce maximum electron energies as predicted by simple one-dimensional theory. The time to saturation and the saturation amplitude of the plasma wave electric field agrees with the Rosenbluth-Liu theory. Stimulated Raman scattering does not appear to degrade the electron acceleration process. Eventually self-focussing and filamentation limit the lifetime of the coherent plasma wave to tens of picoseconds for an intense CO/sub 2/ laser beam.
    12/1983
  • J. M. Kindel, C. Barnes, D. W. Forslund
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    ABSTRACT: There are at least four candidate instabilities which might account for anomalous dc resistivity in the auroral ionosphere. These are: the ion-acoustic instability, the Buneman instability, the ion-cyclotron instability and double layers. A description is given of the results of computer simulations of these four instabilities which suggest that double layers are most likely to be responsible for resistivity in the auroral zone.
    02/1981;
  • J M Kindel, C Barnes, D W Forslund
    01/1981: pages 296;
  • R L Carman, D W Forslund, J M Kindel
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    ABSTRACT: First observed visible harmonics of COâ-laser-irradiated plane and microballoon targets are reported. For intensities >5 x 10¹⁴ W/cm², the harmonic production efficiency is constant over several visible harmonics with a cutoff at a high harmonic number. Two-dimensional particle simulations performed where there is a highly steepened density profile show a flat spectrum for high harmonics, with a cutoff at the harmonic where the upper density shelf is underdense. Harmonics thus offer a means of measuring the upper density shelf and its dynamics.
    Physical Review Letters 01/1981; 46(1):29-32. · 7.73 Impact Factor
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    ABSTRACT: When an electron distribution drifts relative to the ions along a d.c. magnetic field, it is known that, above some critical drift velocity, a nearly field-aligned electromagnetic ion cyclotron instability may be excited. We extend the study of this instability over wide variations in plasma parameters, ion β in particular, and beyond marginal stability.Above threshold the most unstable waves propagate very obliquely to the ambient d.c. magnetic field at wavenumbers of the order of an inverse ion Larmor radius. At low ion β the critical electron drift normalized to the ion thermal velocity scales inversely as β i- ½ while, for β i>10-2, the critical drift scales as the ion thermal velocity. For the Te≈Tielectromagnetic ion cyclotron instabifity begins to have a lower threshold than the corresponding electrostatic instability at β i≈me/Mi. In a moderately high β i, homogeneous, collisionless plasma the electromagnetic ion cyclotron instability appears to have the lowest threshold of any current driven instability.
    Journal of Plasma Physics 01/1979; 21(01):127 - 139. · 0.76 Impact Factor
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    ABSTRACT: Recently extremely large supersonic amplitude ion waves have been observed in simulations of backscatter instabilities, electron beam interactions, and large amplitude Langmuir waves, which break in an unconventional symmetrical x-type manner. The conditions necessary for this type of breaking and simulations to support this theory are presented.
    Physics of Fluids. 01/1979; 22:462-465.
  • J. M. Kindel, M. A. Stroscio
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    ABSTRACT: Two double-pusher laser fusion targets are investigated, one that incorporates an outer exploding pusher shell and another that uses velocity multiplication. Specific designs are presented for the Los Alamos Scientific Laboratory Eight-Beam Laser System.
    NASA STI/Recon Technical Report N. 02/1978; 78:30577.
  • Journal of the Optical Society of America 01/1978; 68.