Relativistic Electron Beam Propagation in the Ion Focusing Regime PDF Download
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Author: J. R. Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 36
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Book Description
This report presents observations on propagation of a mildly relativistic electron beam (gamma = 2.4) in several different gases (air, Helium, Nitrogen, Argon) at low pressure (10-320 mTorr). At such low pressures, and with beam currents of several kiloamperes, beam induced ionization may result in self focusing of an electron beam. Beams propagating under this condition are said to be in the ion focusing regime of propagation. The injected beam has an rms radius of 0.7 cm and a transverse temperature of 35 keV. Beam transport efficiency was measured for He, N2 and Ar. A simple calculation was performed to determine the space charge neutralization fraction as a function of time. Using the results of this calculation, the charge transport efficiency is found and compared with the experimentally measured quantity. Keywords: Electron Beam; Ion Focused Regime.
Author: J. R. Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 36
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Book Description
This report presents observations on propagation of a mildly relativistic electron beam (gamma = 2.4) in several different gases (air, Helium, Nitrogen, Argon) at low pressure (10-320 mTorr). At such low pressures, and with beam currents of several kiloamperes, beam induced ionization may result in self focusing of an electron beam. Beams propagating under this condition are said to be in the ion focusing regime of propagation. The injected beam has an rms radius of 0.7 cm and a transverse temperature of 35 keV. Beam transport efficiency was measured for He, N2 and Ar. A simple calculation was performed to determine the space charge neutralization fraction as a function of time. Using the results of this calculation, the charge transport efficiency is found and compared with the experimentally measured quantity. Keywords: Electron Beam; Ion Focused Regime.
Author: Valery B. Krasovitskii
Publisher: Nova Publishers
ISBN: 9781600215292
Category : Science
Languages : en
Pages : 218
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Book Description
This volume presents the non-linear theory of electrostatic focusing of an electron beam split into bunches under conditions when the plasma permittivity at the modulation frequency is negative and the effective Coulomb force acting on the electron bunches is reversed. Conditions for the spatial equilibrium between the bunch and plasma emission, as well as the dynamics of the formation of focussed bunches, are confirmed by solving (both analytically and numerically) the self-consistent set of equations.
Author: J. Miller
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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An experimental study has been undertaken in order to investigate plasma wakefield effects produced in intense electron beam propagation in a background plasma. A 2 MeV, 1 kA, electron beam is used for this experiment. A 50 cm diam., 3.6 m long drift tube is filled with a background gas, typically trimethylamine (TMA). This gas is ionized by electrons emitted from heated tungsten filaments which are biased at approximately -100 Volts. The resultant plasma density is fairly uniform and is adjustable in the range 10 to the 8th power to 5 x 10 to the 9th power per cubic cm. A higher density Ion Focused Regime (IFR) channel for electron beam propagation is generated by KrF-laser (248 nm) ionization of the background TMA gas. The intense electron beam propagating on an IFR channel in this background plasma experiences wakefield effects due to the natural oscillations of the background plasma which are excited by the beam current risetime. The Ez component of the induced field is responsible for producing beam current modulation near the background plasma frequency. The results scale with plasma density as expected and current modulation is nearly complete for a certain parameter range. This technique may be amenable to a high power microwave generation technique analogous to the relativistic klystron. Detailed experimental results of beam modulation will be presented.
Author:
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Category :
Languages : en
Pages :
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The IFR is a well-known stable, low pressure (0.10 to 0.120 torr in air) propagation window. Secondary electrons created by collisions of beam electrons with gas atoms are rapidly expelled by the strong radial electric field of the beam charge. The ions that remain inside the beam partially neutralize the electric field, allowing magnetic pinch forces to focus the beam. Experiments with the ETA beam have re-verified this stable window and are reported. Image forces from a close wall IFR propagation tank are also experimentally shown to center the beam and damp transverse oscillations. Results of experiments using 5 and 15 cm dia beam tubes are reported. For p tau> 2 torr-nsec (gas pressure x time into pulse the beam charge becomes completely neutralized by the ions, allowing a build up of plasma and resultant beam-plasma instabilities. The onset of these instabilities has been measured using rf pickup loops (0 to 2 GHz) and microwave detectors (6 to 40 GHz), and are also reported.
Author: STEPHEN BRIAN SWANEKAMP
Publisher:
ISBN:
Category :
Languages : en
Pages : 258
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and provides a new and interesting view of IFR beam transport.
Author: R. F. Schneider
Publisher:
ISBN:
Category :
Languages : en
Pages : 15
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Book Description
Charge neutralized electron beam propagation in ionized gases has been studied recently at several laboratories. Such propagation in which the background plasma ions serve to neutralize the charge of tghe beam electrons is said to be the ion focused regime (IFR). There are currently several methods employed to create the background plasma channel through which the beam will propagate. The first is a beam induced plasma channel, the second is a low energy electron beam excited plasma, and the third is a laser initiated plasma channel. With the second and third methods, a pre-ionized channel is provided so that the beam space charge field will eject the plasma electrons leaving the positive ion channel. With the first method, the beam electrons leaving the positive ion channel. With the first method, the beam electrons themselves ionize the gas along the channel, so that much of the beam front is scattered by the higher pressure gas required leaving only a fraction of the pulse length to propagate. Of these methods, only the first, a beam induced plasma channel, is utilized in this work. A parallel reference gives much of the background for this work, and a subsequent paper will discuss results with a low energy electron beam excited channel.
Author: Nikita Wells
Publisher:
ISBN:
Category : Electron beams
Languages : en
Pages : 100
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Book Description
Soviet research on the propagation of intense relativistic electron beams (IREB) through fairly high-pressure air (pressure range 0.1 to 760 Torr) since the early 1970s has included the study of the plasma channel created by the passage of the electron beam through air, the resistive hose instability and its effect on beam propagation, the effect of self-fields, current enhancement, gas expansion, return currents, inherent beam energy spread, and other factors. This report covers Soviet developments in IREB propagation through air where the beam is not focused by external magnetic fields. The information was obtained from Soviet open-source publications with emphasis given to the last ten years of beam propagation in the Soviet Union. The volume of papers published on this subject in recent years indicates a significant increase in Soviet research in this area.
Author:
Publisher:
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Category :
Languages : en
Pages :
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A new general relativistic fluid formulation has been obtained for intense relativistic electron beams (IREB) with arbitrarily high relativistic mass factor ..gamma ... This theory is valid for confined IREB equilibria such as those found inside high energy accelerators as well as in the pinched and ion-focused regimes of beam propagation in plasma channels. The new relativistic fluid formulation is based on the covariant relativistic fluid formulation of Newcomb with the parameter lambda identical to 1, in order to allow for realistic confined equilibria. The resulting equilibrium constraints require that the beam has a slow rotational velocity around its direction of propagation and that the off-diagonal thermal stress element, associated with these two directions of motion, be nonzero. The effective betatron oscillation frequency of the fluid elements of the beam is modified by the radial gradient and anisotropies in the thermal stress elements of the beam fluid. The wave equation, for sausage, hose and filamentation excitations on the relativistic fluid beam, is found to be formally identical to that obtained from the Vlasov equation approach, hence phase-mixing damping is a generic and self-consistent correlate of the new relativistic fluid formulation.
Author: Patrick Gerard O'Shea
Publisher:
ISBN:
Category : Electron beams
Languages : en
Pages : 316
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Author: David Andrew Hammer
Publisher:
ISBN:
Category : Electron beams
Languages : en
Pages : 298
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