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

Title: Measurements of bremsstrahlung production and x-ray cryostat heating in VENUS

Abstract

The VENUS superconducting electron cyclotron resonance (ECR) ion source is designed to operate at 28 GHz with up to 10 kW of rf power. Most of this power is absorbed by the plasma electrons and then dumped onto the plasma chamber wall. The distribution of heating and bremsstrahlung production is highly nonuniform and reflects the geometry of the magnetic confinement fields. The nonuniform distribution of electron losses to the wall results in localized heating on the aluminum chamber walls, which can lead to burnout. In addition, part of the bremsstrahlung produced by the collision of the hot-electrons with the walls is absorbed by the cold mass of the superconducting magnet leading to an additional heat load in the cryostat in the order of several watts. Therefore a new plasma chamber has been installed that incorporates a high-Z tantalum shield to reduce the cryostat heating and enhance water cooling to minimize the chance of burnout. In order to better understand the heat load, the spectrum of the bremsstrahlung has been carefully measured as a function of rf power, magnetic confinement, and rf frequency. In addition, the distribution of electron heating in VENUS magnetic field has been simulated with a three-dimensional computermore » code [H. Heinen and H. J. Andra, Proceedings of the 14th International Workshop on ECR Sources (CERN, Geneva, 1999), 224; H. J. Andra and A. Heinen, Proceedings of the 15th International Workshop on ECR lon Sources, ECRIS'02 (Jyvaeskylae, Finland 2002), 85.] to better understand the heat load distribution on the plasma chamber wall. The new plasma chamber design, results of the bremsstrahlung measurements, and the effectiveness of the high-Z shielding are described.« less

Authors:
; ; ; ; ; ;  [1];  [2];  [3]
  1. Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720 (United States)
  2. (Germany)
  3. (JYFL), FI-40014, University of Jyvaeskylae, Jyvaeskylae (Finland)
Publication Date:
OSTI Identifier:
20778982
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 77; Journal Issue: 3; Conference: 11. international conference on ion sources, Caen (France), 12-16 Sep 2005; Other Information: DOI: 10.1063/1.2163870; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BREMSSTRAHLUNG; COMPUTER CODES; CRYOSTATS; DESIGN; DISTRIBUTION; ECR ION SOURCES; ELECTRON CYCLOTRON-RESONANCE; ELECTRONS; HEATING; HEATING LOAD; MAGNETIC CONFINEMENT; MAGNETIC FIELDS; PLASMA; RF SYSTEMS; SUPERCONDUCTING MAGNETS; TANTALUM; THREE-DIMENSIONAL CALCULATIONS; X RADIATION

Citation Formats

Lyneis, C., Leitner, D., Todd, D., Virostek, S., Loew, T., Heinen, A., Tarvainen, O., Institute of Nuclear Physics, Wilhelm-Klemm-Strasse, 9, D-48149, Muenster, and Department of Physics. Measurements of bremsstrahlung production and x-ray cryostat heating in VENUS. United States: N. p., 2006. Web. doi:10.1063/1.2163870.
Lyneis, C., Leitner, D., Todd, D., Virostek, S., Loew, T., Heinen, A., Tarvainen, O., Institute of Nuclear Physics, Wilhelm-Klemm-Strasse, 9, D-48149, Muenster, & Department of Physics. Measurements of bremsstrahlung production and x-ray cryostat heating in VENUS. United States. doi:10.1063/1.2163870.
Lyneis, C., Leitner, D., Todd, D., Virostek, S., Loew, T., Heinen, A., Tarvainen, O., Institute of Nuclear Physics, Wilhelm-Klemm-Strasse, 9, D-48149, Muenster, and Department of Physics. Wed . "Measurements of bremsstrahlung production and x-ray cryostat heating in VENUS". United States. doi:10.1063/1.2163870.
@article{osti_20778982,
title = {Measurements of bremsstrahlung production and x-ray cryostat heating in VENUS},
author = {Lyneis, C. and Leitner, D. and Todd, D. and Virostek, S. and Loew, T. and Heinen, A. and Tarvainen, O. and Institute of Nuclear Physics, Wilhelm-Klemm-Strasse, 9, D-48149, Muenster and Department of Physics},
abstractNote = {The VENUS superconducting electron cyclotron resonance (ECR) ion source is designed to operate at 28 GHz with up to 10 kW of rf power. Most of this power is absorbed by the plasma electrons and then dumped onto the plasma chamber wall. The distribution of heating and bremsstrahlung production is highly nonuniform and reflects the geometry of the magnetic confinement fields. The nonuniform distribution of electron losses to the wall results in localized heating on the aluminum chamber walls, which can lead to burnout. In addition, part of the bremsstrahlung produced by the collision of the hot-electrons with the walls is absorbed by the cold mass of the superconducting magnet leading to an additional heat load in the cryostat in the order of several watts. Therefore a new plasma chamber has been installed that incorporates a high-Z tantalum shield to reduce the cryostat heating and enhance water cooling to minimize the chance of burnout. In order to better understand the heat load, the spectrum of the bremsstrahlung has been carefully measured as a function of rf power, magnetic confinement, and rf frequency. In addition, the distribution of electron heating in VENUS magnetic field has been simulated with a three-dimensional computer code [H. Heinen and H. J. Andra, Proceedings of the 14th International Workshop on ECR Sources (CERN, Geneva, 1999), 224; H. J. Andra and A. Heinen, Proceedings of the 15th International Workshop on ECR lon Sources, ECRIS'02 (Jyvaeskylae, Finland 2002), 85.] to better understand the heat load distribution on the plasma chamber wall. The new plasma chamber design, results of the bremsstrahlung measurements, and the effectiveness of the high-Z shielding are described.},
doi = {10.1063/1.2163870},
journal = {Review of Scientific Instruments},
number = 3,
volume = 77,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • No abstract prepared.
  • Five cases of X ray observations from balloons coordinated with measurements of precipitating electrons were obtained during passes of the polar-orbiting satellite P78-1 near Siple, Antarctica (L--4.1), the launch point of the balloons. The observations, made during a geomagnetically quiet period in late December 1980 to early January 1981, showed small enhancements of the X ray fluxes (E>25 keV) and moderate trapped electron fluxes (E>68 keV) with pitch angle distributions extending into the edge of the loss cone sufficient to produce the approx. <0.5 dB of cosmic noise absorption recorded by the Siple 30-MHz riometer. Bremsstrahlung production and transport inmore » the atmosphere were calculated using the measured electron fluxes, energy spectra, and pitch angle distributions for the source. The X ray fluxes and spectra calculated for the balloon altitudes were in good agreement with those measured from the balloons when the total energy deposition from electrons, E>10 keV, exceeded 2 x 10/sup -3/ erg/cm/sup 2/ s. The observed electron fluxes show that a significant continuous electron precipitation occurs at the western edge of the South Atlantic magnetic anomaly even at times of low geomagnetic activity.« less
  • The production rates of hard X-rays and the gamma-ray continuum by protons during solar flares are computed exactly, paying special attention to the Lorentz transformation of the radiation. The maximal quantum of the radiation in proton-electron bremsstrahlung is addressed, and angle and energy differential cross sections of X-rays and gamma rays and the rates of these radiations in the thick-target model are presented. A model is proposed for solar X-rays and gamma-rays. It is found that when an energetic proton interacts with an ambient electron, there is a maximum of energy of the emitted photon in each direction whose highestmore » value is in the direction in which the photon is moving and whose lowest value is on the opposite side. At small angles the maximal energy is greater than the energy of an electron having the same velocity as the proton. 42 references.« less