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Title: Radio frequency injection system for electron-cyclotron-resonance ion source in a hostile environment

Abstract

In the framework of the Systeme de Production d'Ions Radioactifs Acceleres en Ligne Phase II (SPIRAL II) project, one of the ion sources which produce 1+ ions is an electron-cyclotron-resonance ion source (ECRIS). The source is installed in a region where the dose rate is such that the radiation hardness is very important for the materials used. Moreover, the proximity of the UC{sub x} target leads to additional constraints as potential surface pollution. A radiation-hard ECRIS has been designed, and the rf injection is under study. The results of rf injection with a wave guide and with an antenna will be presented. The performance obtained with both injection systems combined with the environmental constraints have led us to inject the rf using an antenna. The last point consists in designing a wave guide able to transport the rf through the shielding of the SPIRAL II plug. Design constraints, tests, and the current state of the project will be presented.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1]
  1. Grand Accelerateur National d'Ions Lourds (GANIL), Boulevard Henri Becquerel, B.P. 55027, 14076 Caen Cedex 5 (France)
Publication Date:
OSTI Identifier:
20778983
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: 10.1063/1.2174803; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ANTENNAS; CLOSURES; DESIGN; DOSE RATES; ECR ION SOURCES; HARDNESS; IONS; PARTICLE BEAMS; PERFORMANCE; RADIOWAVE RADIATION; SURFACES

Citation Formats

Huet-Equilbec, C., Jardin, P., Saint Laurent, M. G., Barue, C., Canet, C., Cornell, J.C., Dubois, M., Dupuis, M., Eleon, C., Flambard, J.-L., Gaubert, G., Lecacheux, P., Lecesne, N., Leherissier, P., Lemagnen, F., Leroy, R., Pacquet, J.Y., and Penescu, L. Radio frequency injection system for electron-cyclotron-resonance ion source in a hostile environment. United States: N. p., 2006. Web. doi:10.1063/1.2174803.
Huet-Equilbec, C., Jardin, P., Saint Laurent, M. G., Barue, C., Canet, C., Cornell, J.C., Dubois, M., Dupuis, M., Eleon, C., Flambard, J.-L., Gaubert, G., Lecacheux, P., Lecesne, N., Leherissier, P., Lemagnen, F., Leroy, R., Pacquet, J.Y., & Penescu, L. Radio frequency injection system for electron-cyclotron-resonance ion source in a hostile environment. United States. doi:10.1063/1.2174803.
Huet-Equilbec, C., Jardin, P., Saint Laurent, M. G., Barue, C., Canet, C., Cornell, J.C., Dubois, M., Dupuis, M., Eleon, C., Flambard, J.-L., Gaubert, G., Lecacheux, P., Lecesne, N., Leherissier, P., Lemagnen, F., Leroy, R., Pacquet, J.Y., and Penescu, L. Wed . "Radio frequency injection system for electron-cyclotron-resonance ion source in a hostile environment". United States. doi:10.1063/1.2174803.
@article{osti_20778983,
title = {Radio frequency injection system for electron-cyclotron-resonance ion source in a hostile environment},
author = {Huet-Equilbec, C. and Jardin, P. and Saint Laurent, M. G. and Barue, C. and Canet, C. and Cornell, J.C. and Dubois, M. and Dupuis, M. and Eleon, C. and Flambard, J.-L. and Gaubert, G. and Lecacheux, P. and Lecesne, N. and Leherissier, P. and Lemagnen, F. and Leroy, R. and Pacquet, J.Y. and Penescu, L.},
abstractNote = {In the framework of the Systeme de Production d'Ions Radioactifs Acceleres en Ligne Phase II (SPIRAL II) project, one of the ion sources which produce 1+ ions is an electron-cyclotron-resonance ion source (ECRIS). The source is installed in a region where the dose rate is such that the radiation hardness is very important for the materials used. Moreover, the proximity of the UC{sub x} target leads to additional constraints as potential surface pollution. A radiation-hard ECRIS has been designed, and the rf injection is under study. The results of rf injection with a wave guide and with an antenna will be presented. The performance obtained with both injection systems combined with the environmental constraints have led us to inject the rf using an antenna. The last point consists in designing a wave guide able to transport the rf through the shielding of the SPIRAL II plug. Design constraints, tests, and the current state of the project will be presented.},
doi = {10.1063/1.2174803},
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}
}
  • The ion current achievable from high intensity ECR sources for highly charged ions is limited by the high space charge. This makes classical extraction systems for the transport and subsequent matching to a radio frequency quadrupole (RFQ) accelerator less efficient. The direct plasma injection (DPI) method developed originally for the laser ion source avoids these problems and uses the combined focusing of the gap between the ion source and the RFQ vanes (or rods) and the focusing of the rf fields from the RFQ penetrating into this gap. For high performance ECR sources that use superconducting solenoids, the stray magneticmore » field of the source in addition to the DPI scheme provides focusing against the space charge blow-up of the beam. A combined extraction/matching system has been designed for a high performance ECR ion source injecting into an RFQ, allowing a total beam current of 10 mA from the ion source for the production of highly charged {sup 238}U{sup 40+} (1.33 mA) to be injected at an ion source voltage of 60 kV. In this design, the features of IGUN have been used to take into account the rf-focusing of an RFQ channel (without modulation), the electrostatic field between ion source extraction and the RFQ vanes, the magnetic stray field of the ECR superconducting solenoid, and the defocusing space charge of an ion beam. The stray magnetic field is shown to be critical in the case of a matched beam.« less
  • To meet the requirements of developing separated function radio frequency quadruple (rfq) and upgrading the 1 MeV integral split ring rfq accelerator, an electron cyclotron resonance O{sup +} ion source and low energy beam transport (LEBT) system have been developed. Using two Einzel lenses to focus the beam, more than 6 mA O{sup +} peak beam current with energy of 22 keV can be easily obtained at the end of LEBT when the duty faction is at 1/6. The normalized root-mean-square emittance of 90% of the beam is about 0.12{pi} mm mrad. By changing the focusing power of lenses, themore » beam waist can be shifted from 80 mm before the beam diaphragm 2 to 80 mm after it. The experimental results will be presented in this article.« less
  • The electromagnetic field within the plasma chamber of an electron cyclotron resonance ion source (ECRIS) and the properties of the plasma waves affect the plasma properties and ion beam production. We have experimentally investigated the ''frequency tuning effect'' and ''double frequency heating'' on the CAPRICE ECRIS device. A traveling wave tube amplifier, two microwave sweep generators, and a dedicated experimental set-up were used to carry out experiments in the 12.5-16.5 GHz frequency range. During the frequency sweeps the evolution of the intensity and shape of the extracted argon beam were measured together with the microwave reflection coefficient. A range ofmore » different ion source parameter settings was used. Here we describe these experiments and the resultant improved understanding of these operational modes of the ECR ion source.« less
  • The properties of the electromagnetic waves heating the electrons of the ECR ion sources (ECRIS) plasma affect the features of the extracted ion beams such as the emittance, the shape, and the current, in particular for higher charge states. The electron heating methods such as the frequency tuning effect and the double frequency heating are widely used for enhancing the performances of ECRIS or even for the routine operation during the beam production. In order to better investigate these effects the CAPRICE ECRIS has been operated using these techniques. The ion beam properties for highly charged ions have been measuredmore » with beam diagnostic tools. The reason of the observed variations of this performance can be related to the different electromagnetic field patterns, which are changing inside the plasma chamber when the frequency is varying.« less
  • To investigate the transition from the low density mode to the high density mode in an electron cyclotron resonance (ECR) discharge, a Langmuir probe and an {ital E} field probe were used to measure ion density and {ital E} field intensity as functions of axial position and power. The experiments were performed in argon at 0.13 Pa in a 7.9 cm diam cyclindrical source chamber propagating TE{sub 11} mode 2.45 GHz microwave power. Low mode was characterized by a standing wave throughout the plasma chamber and minimal power absorption. High mode exhibited nearly complete power absorption and no standing wavemore » past the ECR zone. A sliding short (ss) was used to determine if the position of an {ital E} field null in the source chamber affected the transition between these two modes for various magnetic field configurations. The ss position had little effect on mode transition, relative power absorption or ion density when positioned downstream from a broad, large volume resonance zone (resonance near the mirror midplane). However, the plasma could not be ignited if the short was placed at or upstream from the large volume resonance zone.« less