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Title: Recent performance of the SNS H{sup −} ion source and low-energy beam transport system

Abstract

Recent measurements of the H{sup −} beam current show that SNS is injecting about 55 mA into the RFQ compared to ∼45 mA in 2010. Since 2010, the H{sup −} beam exiting the RFQ dropped from ∼40 mA to ∼34 mA, which is sufficient for 1 MW of beam power. To minimize the impact of the RFQ degradation, the service cycle of the best performing source was extended to 6 weeks. The only degradation is fluctuations in the electron dump voltage towards the end of some service cycles, a problem that is being investigated. Very recently, the RFQ was retuned, which partly restored its transmission. In addition, the electrostatic low-energy beam transport system was reengineered to double its heat sinking and equipped with a thermocouple that monitors the temperature of the ground electrode between the two Einzel lenses. The recorded data show that emissions from the source at high voltage dominate the heat load. Emissions from the partly Cs-covered first lens cause the temperature to peak several hours after starting up. On rare occasions, the temperature can also peak due to corona discharges between the center ground electrode and one of the lenses.

Authors:
; ; ; ; ; ; ;  [1]
  1. Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
Publication Date:
OSTI Identifier:
22253522
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 85; Journal Issue: 2; Conference: ICIS 2011: 14. international conference on ion sources, Giardini-Naxos, Sicily (Italy), 12-16 Sep 2011; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM CURRENTS; BEAM TRANSPORT; CORONA DISCHARGES; ELECTRIC POTENTIAL; ELECTRODES; ELECTRONS; HEATING LOAD; ION SOURCES; LENSES; START-UP; THERMOCOUPLES

Citation Formats

Stockli, Martin P., E-mail: stockli@ornl.gov, Ewald, K. D., Han, B. X., Murray, S. N., Pennisi, T. R., Piller, C., Santana, M., Tang, J., and Welton, R. Recent performance of the SNS H{sup −} ion source and low-energy beam transport system. United States: N. p., 2014. Web. doi:10.1063/1.4862205.
Stockli, Martin P., E-mail: stockli@ornl.gov, Ewald, K. D., Han, B. X., Murray, S. N., Pennisi, T. R., Piller, C., Santana, M., Tang, J., & Welton, R. Recent performance of the SNS H{sup −} ion source and low-energy beam transport system. United States. https://doi.org/10.1063/1.4862205
Stockli, Martin P., E-mail: stockli@ornl.gov, Ewald, K. D., Han, B. X., Murray, S. N., Pennisi, T. R., Piller, C., Santana, M., Tang, J., and Welton, R. 2014. "Recent performance of the SNS H{sup −} ion source and low-energy beam transport system". United States. https://doi.org/10.1063/1.4862205.
@article{osti_22253522,
title = {Recent performance of the SNS H{sup −} ion source and low-energy beam transport system},
author = {Stockli, Martin P., E-mail: stockli@ornl.gov and Ewald, K. D. and Han, B. X. and Murray, S. N. and Pennisi, T. R. and Piller, C. and Santana, M. and Tang, J. and Welton, R.},
abstractNote = {Recent measurements of the H{sup −} beam current show that SNS is injecting about 55 mA into the RFQ compared to ∼45 mA in 2010. Since 2010, the H{sup −} beam exiting the RFQ dropped from ∼40 mA to ∼34 mA, which is sufficient for 1 MW of beam power. To minimize the impact of the RFQ degradation, the service cycle of the best performing source was extended to 6 weeks. The only degradation is fluctuations in the electron dump voltage towards the end of some service cycles, a problem that is being investigated. Very recently, the RFQ was retuned, which partly restored its transmission. In addition, the electrostatic low-energy beam transport system was reengineered to double its heat sinking and equipped with a thermocouple that monitors the temperature of the ground electrode between the two Einzel lenses. The recorded data show that emissions from the source at high voltage dominate the heat load. Emissions from the partly Cs-covered first lens cause the temperature to peak several hours after starting up. On rare occasions, the temperature can also peak due to corona discharges between the center ground electrode and one of the lenses.},
doi = {10.1063/1.4862205},
url = {https://www.osti.gov/biblio/22253522}, journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 2,
volume = 85,
place = {United States},
year = {Sat Feb 15 00:00:00 EST 2014},
month = {Sat Feb 15 00:00:00 EST 2014}
}