WorldCat Identities

Serlin, V.

Works: 10 works in 10 publications in 1 language and 10 library holdings
Publication Timeline
Most widely held works by V Serlin
Relativistic Klystron Amplifiers Driven by Modulated Intense Relativistic Electron Beams( Book )

1 edition published in 1990 in English and held by 1 WorldCat member library worldwide

This paper, gives an overview of the novel relativistic klystron amplifiers which are driven by an annular intense relativistic electron beam (500 kV, 10 kA range) which is modulated by an external rf source (1.3 GHz, 100 kW range). Experiments, theory, simulation and simple models are presented to illustrate the unusual properties of such devices, which result from the intense space charge of the beam. Chief among them include electrostatic insulation against vacuum breakdown at high power levels, efficient current modulation, short bunching length, and amplitude and phase stability of the output signal. Many of these unexpected features were revealed in two separate experiments: one with the lower current beam (5 kA, 2 cm beam radius), and the other one with a higher current beam (16 kA, 6.6 cm beam radius). Three gigawatts or rf power at 1.3 GHz were generated with the large diameter beam at an efficiency of 35 percent with 37 dB gain. These experiments will be reviewed, along with a combination of particle simulation results and analytic models which facilitate the interpretation. Pay special attention to the unfamiliar features of these amplifiers, and shall address the critical issues which need to be solved before such amplifiers can fulfill their potential in a wide range of applications. Keywords: High power microwaves; Relativistic klystron amplifiers; Intense beam modulation. (JHD)
Simulation Studies of Particle Acceleration Powered by Modulated Intense Relativistic Electron Beams( Book )

1 edition published in 1989 in English and held by 1 WorldCat member library worldwide

A time dependent, fully electromagnetic particle code is used to simulate transfer of energy from an annular modulated intense relativistic electron beam to a low current electron beam via a disk-loaded structure. It is shown that an intense beam may be used to drive such an accelerator at high transformer ratio (R 10) to obtain accelerating gradients in the about 100 Mv/m range, with power excess of 1 GW transferred from the primary to the secondary beam. Keywords: Particle accelerators; Compact accelerators; Particle simulations; Intense relativistic electron beams. (JHD)
Direct Observation of Mass Oscillations Due to Ablative Richtmyer-Meshkov Instability in Plastic Targets( )

1 edition published in 2002 in English and held by 0 WorldCat member libraries worldwide

We report the first direct experimental observation of the ablative Richtmyer-Meshkov instability. It manifests itself in oscillations of areal mass that occur during the shock transit time, which are caused by the rocket effect or dynamic overpressure characteristic of interaction between the laser absorption zone and the ablation front. With the 4 ns long Nike KrF laser pulse and our novel diagnostic technique (monochromatic x-ray imaging coupled to a streak camera) we were able to register a peak and a valley of the areal mass variation before the observed onset of the Rayleigh-Taylor growth
Direct Observation of Mass Oscillations due to Ablative Richtmyer-Meshkov Instability and Feedout in Planar Plastic Targets( )

1 edition published in 2002 in English and held by 0 WorldCat member libraries worldwide

Perturbations that seed Rayleigh-Taylor (RT) instability in laser-driven targets form during the early-time period. This time includes a shock wave transit from the front to the rear surface of the target, and a rarefaction wave transit in the opposite direction. During this time interval, areal mass perturbations caused by all sources of nonuniformity (laser imprint, surface ripple) are expected to oscillate. The first direct experimental observations of the areal mass oscillations due to ablative Richtmyer-Meshkov (RM) instability and feedout followed by the RT growth of areal mass modulation are discussed. The experiments were made with 40 to 99 mm thick planar plastic targets rippled either on the front or on the rear with a sine wave ripple with either 30 or 45 mm wavelength and with 0.5, 1 or 1.5 mm amplitude. Targets were irradiated with 4 ns long Nike KrF laser pulses at approximately 50 TW/cm2. The oscillations were observed with our novel diagnostic technique, a monochromatic x-ray imager coupled to a streak camera. For the ablative RM instability (front side ripple), the mass modulation amplitude was typically observed to grow, reach a peak, and then decrease, after which the exponential RT growth started. In some cases, one phase reversal due to the ablative RM instability was observed. For the feedout geometry (rear side ripple), in all cases two phase reversals were observed: a distinct half-oscillation was followed by the onset of the RT growth, resulting in a second phase reversal
Perturbation Evolution Started by Richtmyer-Meshkov Instability in Planar Laser Targets( )

1 edition published in 2006 in English and held by 0 WorldCat member libraries worldwide

The first observations of the interaction of the Richtmyer-Meshkov (RM) instability with reflected shock and rarefaction waves in laser-driven targets are reported. The RM growth is started by a shock wave incident upon a rippled interface between low-density foam and solid plastic. Subsequent interaction of secondary rarefaction and/or shock waves arriving from the ablation front and the rear surface of the target with the RM-unstable interface stops the perturbation growth and reverses its direction. The ensuing exponential Rayleigh-Taylor growth thus can sometimes proceed with an inverted phase
Effects of Thin High-z Layers on the Hydrodynamics of Laser-Accelerated Plastic Targets( )

1 edition published in 2002 in English and held by 0 WorldCat member libraries worldwide

We present experimental results and simulations that study the effects of thin metallic layers with high atomic number (high-Z) on the hydrodynamics of laser accelerated plastic targets. These experiments employ a laser pulse with a low-intensity foot that rises into a high-intensity main pulse. This pulse shape simulates the generic shape needed for high-gain fusion implosions. Imprint of laser nonuniformity during start up of the low intensity foot is a well-known seed for hydrodynamic instability. We observe large reductions in hydrodynamic instability seeded by laser imprint when certain minimum thickness gold or palladium layers are applied to the laser-illuminated surface of the targets. The experiment indicates that the reduction in imprint is at least as large as that obtained by a 6 times improvement in the laser uniformity. We present simulations supported by experiments showing that during the low intensity foot the laser light can be nearly completely absorbed by the high-Z layer. X-rays originating from the high-Z layer heat the underlying lower-Z plastic target material and cause large buffering plasma to form between the layer and the accelerated target. This long-scale plasma apparently isolates the target from laser nonuniformity and accounts for the observed large reduction in laser imprint. With onset of the higher intensity main pulse, the high-Z layer expands and the laser light is transmitted. This technique will be useful in reducing laser imprint in pellet implosions and thereby allow the design of more robust targets for high-gain laser fusion
Laser Plasma Instability Experiments with KrF Lasers( )

1 edition published in 2007 in English and held by 0 WorldCat member libraries worldwide

Deleterious effects of laser-plasma instability (LPI) may limit the maximum laser irradiation that can be used for inertial confinement fusion. The short wavelength (248 nm), large bandwidth, and very uniform illumination available with krypton-fluoride (KrF) lasers should increase the maximum usable intensity by suppressing LPI. The concomitant increase in ablation pressure would allow implosion of low aspect ratio pellets to ignition with substantial gain (>20) at much reduced laser energy. The proposed KrF laser based Fusion Test Facility (FTF) would exploit this strategy to achieve significant fusion power (150 MW) with a rep-rate system that has a per pulse laser energy well below 1 megajoule. Measurements of LPI using the Nike KrF laser are presented at and above intensities needed for the FTF (I~2x1015 W/cm2). The results to date indicate that LPI is indeed suppressed. With overlapped beam intensity above the planar, single beam intensity threshold for the two-plasmon decay instability, no evidence of instability was observed via measurements of 3/2 omega(o) and 1/2 omega(o) harmonic emissions
Classical and Ablative Richtmyer-Meshkov Instability and Other ICF-Relevant Plasma Flows Diagnosed With Monochromatic X-Ray Imaging( )

1 edition published in 2007 in English and held by 0 WorldCat member libraries worldwide

In inertial confinement fusion (ICF) and high-energy density physics (HEDP), the most important manifestations of the hydrodynamic instabilities and other mixing processes involve lateral motion of the accelerated plasmas. In order to understand the experimental observations and to advance the numerical simulation codes to the point of predictive capability, it is critically important to accurately diagnose the motion of the dense plasma mass. The most advanced diagnostic technique recently developed for this purpose is the monochromatic x-ray imaging that combines large field of view with high contrast, high spatial resolution and large throughput, ensuring high temporal resolution at large magnification. Its application made it possible for the experimentalists to observe for the first time important hydrodynamic effects that trigger compressible turbulent mixing in laser targets, such as ablative Richtmyer-Meshkov (RM) instability, feedout, interaction of a RM-unstable interface with rarefaction waves. It also helped to substantially improve the accuracy of diagnosing many other important plasma flows, ranging from laser-produced jets to electromagnetically driven wires in a Z-pinch, and to test various methods suggested for mitigation of the Rayleigh-Taylor instability. We will review the results obtained with the aid of this technique in ICF-HEDP studies at the Naval Research Laboratory and the prospects of its future applications
Simulation Studies of a Klystronlike Amplifier Operating in the 10-100 GW Regime( )

1 edition published in 1990 in English and held by 0 WorldCat member libraries worldwide

A coaxial drift tube allows propagation of an ultra high power relativistic electron beam (500 keV,> or = 100 kA, 100 ns). This paper covers the modulation of a large diameter (12.6 cm) intense relativistic electron beam (500 keV, 16 ka) by an external microwave source via particle simulation. The annular beam, enclosed within a coaxial drift tube, is found to be fully modulated by a low-power external rf source at a frequency of 1.3 GHz. For such an intense beam, a highly nonlinear interaction takes place at the modulating gap, producing highly coherent bunches of electrons. This finding is similar to earlier research in which such modulation was studied for an intense beam propagating in a hollow drift tube. Unlike the hollow drift tube case, the coaxial configuration is easily scaled to high power. Here, a very large diameter (26 cm) intense beam (460 keV, 100 kA) is fully modulated at 1.3 GHz to obtain 31 GW of rf beam power
Direct Observation of Feedout-Related Mass Oscillations in Plastic Targets( )

1 edition published in 2001 in English and held by 0 WorldCat member libraries worldwide

Feedout means the transfer of mass perturbations from the rear to the front surface of a driven target. When a planar shock wave breaks out at a rippled rear surface of the target, a lateral pressure gradient drives sonic waves in a rippled rarefaction wave propagating back to the front surface. This process redistributes mass in the volume of the target, forming the feedout-generated seed for ablative Rayleigh-Taylor (RT) instability. We report the first direct experimental observation of areal mass oscillation associated with feedout, followed by the onset of exponential RT growth
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English (10)