Download or read book Electron Beam Propagation in the Ion Focused Regime IFR with the Experimental Test Accelerator ETA written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Transverse Oscillations Observed in IFR Ion Focused Regime Electron Beam Propagation written by R. F. Schneider and published by . This book was released on 1986 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simulation of Electron Beam Transport in Ion Focused Regime Conditioning Cells written by and published by . This book was released on 1992 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: The resistive hose instability can disrupt propagation of self- pinched beams in dense gas. To reduce growth of the instability, beams can be conditioned prior to propagation. The objectives of beam conditioning are to center the beam in order to reduce initial transverse perturbations which seed the hose instability, and to tailor the beam emittance in order to detune the head-to-tail coherence of the instability. Emittance tailoring can be performed by transporting the beam through a passive ion-focused regime (IFR) cell, which induces a head-to-tail taper of the beam radius; the radius taper is then converted to an emittance taper by passing the beam through a thick exit foil which scatters the beam. Beam centering can be accomplished by transporting the beam through either: (1) a passive IFR cell which is narrow enough to provide wall guiding, or (2) a laser-ionized active IFR cell, or (3) a wire cell in which the centering is provided by a current-carrying wire. We report here on axisymmetric particle simulation studies of IFR tailoring cells, alone and in tandem with each of these types of centering cells, and also on the effect of supplementary focusing lenses and conducting foils. We discuss the parameter choices that are conducive to effective beam conditioning. The emphasis is on conditioning configurations and beam parameters that have actually been tested in experiments with the ATA and SuperIBEX accelerators.
Download or read book INIS Atomindex written by and published by . This book was released on 1987 with total page 1214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific Program and Abstracts written by and published by . This book was released on 1985 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Relativistic Electron Beam Propagation in the Ion Focusing Regime written by J. R. Smith and published by . This book was released on 1986 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Intense Electron beam Transport in the Ion focused Regime Through the Collision dominated Regime written by and published by . This book was released on 1993 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper reviews the transport of the 19-MeV, 700-kA, 25-ns Hermes-III electron beam in long gas cells filled with N2 gas spanning six decades in pressure from 103 to (approximately)103 Torr. We show through measurements and theoretical analyses that the beam has two windows of stable transport: a low-pressure window (between (approximately)1 and (approximately)100 mTorr) that is dominated by propagation in the semi-collisionless IFR (ion-focused regime), and a high-pressure window (between (approximately)1 and (approximately)100 Torr) that is dominated by propagation in the resistive CDR (collision-dominated regime). In the CDR, 79"1.5% of the beam energy is transported over 11 m at 20 Torr. In the IFR, we show that intense radiation fields with controllable rise times and pulse widths can be generated on axis at a bremsstrahlung target. In summary, the measurements and analyses presented here provide a quantitative description of the Hermes-III beam transport over six decades in pressure.
Download or read book Study of Intense Relativistic Electron Beam Modulation by Wakefield Effects written by J. Miller and published by . This book was released on 1991 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Physics Briefs written by and published by . This book was released on 1984 with total page 1120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of Collective Ion Acceleration and Relativistic Electron Beam Propagation written by John Rudolph Smith and published by . This book was released on 1983 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Government Reports Annual Index written by and published by . This book was released on 1984 with total page 1296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1992-09 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book THE THEORY AND SIMULATION OF RELATIVISTIC ELECTRON BEAM TRANSPORT IN THE ION FOCUSED REGIME written by STEPHEN BRIAN SWANEKAMP and published by . This book was released on 1990 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: and provides a new and interesting view of IFR beam transport.
Download or read book Investigation of Ion Beam Production and Acceleration Using Linear Electron Beams and a Pulse Powered Plasma Focus written by MARYLAND UNIV COLLEGE PARK DEPT OF ELECTRICAL ENGINEERING. and published by . This book was released on 1984 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: An intense relativistic electron beam cannot propagate in a metal drift tube when the current exceeds the space charge limit. Very high charge density and electric field gradients (100 to 1000 MV/m) develop at the beam front and the electrons are reflected. When a neutral gas or a plasma is present, collective acceleration of positive ions occur, and the resulting charge neutralization enables the beam to propagate. Experimental results, theoretical understanding, and schemes to achieve high ion energies by external control of the beams front velocity will be reviewed. (Author).
Download or read book Stable Propagation of a High current Electron Beam written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental studies of self-focused, high-current electron-beam propagation phenomena are compared with the results of computational modeling. The model includes the radial structure of the beam-plasma system, a full electromagnetic field description, primary and secondary gas ionization processes, and a linear theory of the hose-like distortions. Good agreement between the experimental results and the computations strengthens the premise that hose instability is the principal limitation to propagation at high pressure.
