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Title: Recent performance and ignition tests of the pulsed SNS H{sup −} source for 1-MW neutron production

Abstract

After acquiring several reliable spare targets, SNS ramped the beam power from 850 kW to 1.4 MW, which required an increase in H{sup −} beam pulse length from 0.88 to 1.0 ms at 60 Hz. This increase initially produced slow 2-MHz power ramp-ups and, after several weeks of uninterrupted operation, it produced plasma outages every time the pulse length was raised above ∼0.95 ms. Similar outages were previously observed towards the end of long service cycles, which were believed to indicate that the breakdown voltage of the high purity hydrogen started to exceed the induced electric fields. In 2011 the RF was reconfigured to start with 10 cycles of 1.96 MHz, which yielded the shortest H{sup −} beam rise times and apparently eliminated those plasma outages. The new, pulse-length dependent outages were eliminated by increasing the initial frequency to 1.985 MHz. However, careful frequency studies are unable to justify this frequency. In addition, the paper discusses the issues and solutions for the electron-dump voltage, which starts to sag and become unstable after several weeks of high current operation. At the request of the authors and the Proceedings Editor this article has been updated to include References 3–13, which were present in the author’s original submissionmore » but were lost during manuscript processing in the Proceedings Editor's office. The updated article was published on 5 May 2015.« less

Authors:
; ; ; ; ; ;  [1]
  1. Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A (United States)
Publication Date:
OSTI Identifier:
22391410
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1655; Journal Issue: 1; Conference: NIBS 2014: 4. International Symposium on Negative Ions, Beams and Sources, Garching (Germany), 6-10 Oct 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BEAM PULSERS; ELECTRIC CURRENTS; ELECTRIC POTENTIAL; ELECTRONS; HYDROGEN; MHZ RANGE; NEUTRON SOURCES; NEUTRONS; OPERATION; OUTAGES; PERFORMANCE; PLASMA; SPALLATION; YIELDS

Citation Formats

Stockli, Martin P., E-mail: stockli@ornl.gov, Han, B. X., Murray, S. N., Pennisi, T. R., Piller, C., Santana, M., and Welton, R. F. Recent performance and ignition tests of the pulsed SNS H{sup −} source for 1-MW neutron production. United States: N. p., 2015. Web. doi:10.1063/1.4916428.
Stockli, Martin P., E-mail: stockli@ornl.gov, Han, B. X., Murray, S. N., Pennisi, T. R., Piller, C., Santana, M., & Welton, R. F. Recent performance and ignition tests of the pulsed SNS H{sup −} source for 1-MW neutron production. United States. doi:10.1063/1.4916428.
Stockli, Martin P., E-mail: stockli@ornl.gov, Han, B. X., Murray, S. N., Pennisi, T. R., Piller, C., Santana, M., and Welton, R. F. 2015. "Recent performance and ignition tests of the pulsed SNS H{sup −} source for 1-MW neutron production". United States. doi:10.1063/1.4916428.
@article{osti_22391410,
title = {Recent performance and ignition tests of the pulsed SNS H{sup −} source for 1-MW neutron production},
author = {Stockli, Martin P., E-mail: stockli@ornl.gov and Han, B. X. and Murray, S. N. and Pennisi, T. R. and Piller, C. and Santana, M. and Welton, R. F.},
abstractNote = {After acquiring several reliable spare targets, SNS ramped the beam power from 850 kW to 1.4 MW, which required an increase in H{sup −} beam pulse length from 0.88 to 1.0 ms at 60 Hz. This increase initially produced slow 2-MHz power ramp-ups and, after several weeks of uninterrupted operation, it produced plasma outages every time the pulse length was raised above ∼0.95 ms. Similar outages were previously observed towards the end of long service cycles, which were believed to indicate that the breakdown voltage of the high purity hydrogen started to exceed the induced electric fields. In 2011 the RF was reconfigured to start with 10 cycles of 1.96 MHz, which yielded the shortest H{sup −} beam rise times and apparently eliminated those plasma outages. The new, pulse-length dependent outages were eliminated by increasing the initial frequency to 1.985 MHz. However, careful frequency studies are unable to justify this frequency. In addition, the paper discusses the issues and solutions for the electron-dump voltage, which starts to sag and become unstable after several weeks of high current operation. At the request of the authors and the Proceedings Editor this article has been updated to include References 3–13, which were present in the author’s original submission but were lost during manuscript processing in the Proceedings Editor's office. The updated article was published on 5 May 2015.},
doi = {10.1063/1.4916428},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1655,
place = {United States},
year = 2015,
month = 4
}
  • After acquiring several reliable spare targets, SNS ramped the beam power from 850 kW to 1.4 MW, which required an increase in H- beam pulse length from 0.88 to 1.0 ms at 60 Hz. This increase initially produced slow 2-MHz power ramp-ups and, after several weeks of uninterrupted operation, it produced plasma outages every time the pulse length was raised above ~0.95 ms. Similar outages were previously observed towards the end of long service cycles, which were believed to indicate that the breakdown voltage of the high purity hydrogen started to exceed the induced electric fields. In 2011 the RFmore » was reconfigured to start with 10 cycles of 1.96 MHz, which yielded the shortest H- beam rise times and apparently eliminated those plasma outages. The new, pulse-length dependent outages were eliminated by increasing the initial frequency to 1.985 MHz. However, careful frequency studies are unable to justify this frequency. In addition, the paper discusses the issues and solutions for the electron-dump voltage, which starts to sag and become unstable after several weeks of high current operation.« less
  • In this paper we describe the latest tests of the MISANS spectrometer at the IPNS in Argonne, USA. At this stage the time resolution and more importantly the contrast of the modulation at the detector is very low, nevertheless it was possible to perform a MISANS-measurement and test some features typical for a pulsed neutron source. The MISANS technique has a huge potential to improve its contrast and resolution towards a high resolution spin echo spectrometer.
  • No abstract prepared.
  • The Intense Pulsed Neutron Source (IPNS) facility has now been operating in a routine way for outside users since November 1, 1981. From that date through December of 1982, the accelerator system was scheduled for neutron science for 4500 hours. During this time the accelerator achieved its short-term goals by delivering about 380,000,000 pulses of beam totaling over 6 x 10/sup 20/ protons. The changes in equipment and operating practices that evolved during this period of intense running are described. The intensity related instability threshold was increased by a factor of two and the accelerator beam current has been ionmore » source limited. Plans to increase the accelerator intensity are also described. Initial operating results with a new HL/sup -/ ion source are discussed.« less