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Title: Effect of ion excape velocity and conversion surface material on H- production

Abstract

According to generally accepted models surface production of negative ions depends on ion escape velocity and work function of the surface. We have conducted an experimental study addressing the role of the ion escape velocity on H{sup -} production. A converter-type ion source at Los Alamos Neutron Science Center was employed for the experiment. The ion escape velocity was changed by varying the bias voltage of the converter electrode. It was observed that due to enhanced stripping of H{sup -} no direct gain of extracted beam current can be achieved by increasing the converter voltage. At the same time the conversion efficiency of H{sup -} was observed to vary with converter voltage and follow the existing theories in qualitative manner. We discuss the role of surface material on H{sup -} formation probability and present calculations predicting relative H{sup -} yields from different cesiated surfaces. These calculations are compared with experimental observations from different types of H{sup -} ion sources. The effects caused by varying cesium coverage are also discussed. Finally, we present a novel idea of utilizing materials exhibiting so-called negative electron affinity in H{sup -}/D{sup -} production under UV-light exposure.

Authors:
 [1];  [1];  [1];  [1];  [1];  [2];  [3];  [4]
  1. Los Alamos National Laboratory
  2. UNIV OF JYVASKYLA
  3. UNIV OF JYASKYLA
  4. ORNL
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1036725
Report Number(s):
LA-UR-10-06737; LA-UR-10-6737
TRN: US1201464
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: 2nd International Symposium on Negative Ions, Beams and Sources ; November 16, 2010 ; Takayama Gifu, Japan
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; AFFINITY; ANIONS; BEAM CURRENTS; CESIUM; EFFICIENCY; ION SOURCES; NEUTRONS; PROBABILITY; PRODUCTION; VELOCITY; WORK FUNCTIONS

Citation Formats

Johnson, Kenneth F, Tarvainen, Olli A, Geros, E., Stelzer, J., Rouleau, G., Kalvas, T., Komppula, J., and Carmichael, J. Effect of ion excape velocity and conversion surface material on H- production. United States: N. p., 2010. Web.
Johnson, Kenneth F, Tarvainen, Olli A, Geros, E., Stelzer, J., Rouleau, G., Kalvas, T., Komppula, J., & Carmichael, J. Effect of ion excape velocity and conversion surface material on H- production. United States.
Johnson, Kenneth F, Tarvainen, Olli A, Geros, E., Stelzer, J., Rouleau, G., Kalvas, T., Komppula, J., and Carmichael, J. Tue . "Effect of ion excape velocity and conversion surface material on H- production". United States. https://www.osti.gov/servlets/purl/1036725.
@article{osti_1036725,
title = {Effect of ion excape velocity and conversion surface material on H- production},
author = {Johnson, Kenneth F and Tarvainen, Olli A and Geros, E. and Stelzer, J. and Rouleau, G. and Kalvas, T. and Komppula, J. and Carmichael, J.},
abstractNote = {According to generally accepted models surface production of negative ions depends on ion escape velocity and work function of the surface. We have conducted an experimental study addressing the role of the ion escape velocity on H{sup -} production. A converter-type ion source at Los Alamos Neutron Science Center was employed for the experiment. The ion escape velocity was changed by varying the bias voltage of the converter electrode. It was observed that due to enhanced stripping of H{sup -} no direct gain of extracted beam current can be achieved by increasing the converter voltage. At the same time the conversion efficiency of H{sup -} was observed to vary with converter voltage and follow the existing theories in qualitative manner. We discuss the role of surface material on H{sup -} formation probability and present calculations predicting relative H{sup -} yields from different cesiated surfaces. These calculations are compared with experimental observations from different types of H{sup -} ion sources. The effects caused by varying cesium coverage are also discussed. Finally, we present a novel idea of utilizing materials exhibiting so-called negative electron affinity in H{sup -}/D{sup -} production under UV-light exposure.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2010},
month = {10}
}

Conference:
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