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Title: Recent Performance and Ignition Tests of the pulsed SNS H- 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- 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- 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.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1185845
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 4th International Symposium on Negative Ions, Beams and Sources, Garching, Germany, 20141006, 20141010
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; Cesium; H- ions; ion source; RF ion source; multicusp ion source

Citation Formats

Stockli, Martin P, Han, Baoxi, Murray, Jr, S N, Pennisi, Terry R, Piller, Chip, Santana, Manuel, and Welton, Robert F. Recent Performance and Ignition Tests of the pulsed SNS H- Source for 1-MW Neutron Production. United States: N. p., 2015. Web.
Stockli, Martin P, Han, Baoxi, Murray, Jr, S N, Pennisi, Terry R, Piller, Chip, Santana, Manuel, & Welton, Robert F. Recent Performance and Ignition Tests of the pulsed SNS H- Source for 1-MW Neutron Production. United States.
Stockli, Martin P, Han, Baoxi, Murray, Jr, S N, Pennisi, Terry R, Piller, Chip, Santana, Manuel, and Welton, Robert F. Thu . "Recent Performance and Ignition Tests of the pulsed SNS H- Source for 1-MW Neutron Production". United States. doi:. https://www.osti.gov/servlets/purl/1185845.
@article{osti_1185845,
title = {Recent Performance and Ignition Tests of the pulsed SNS H- Source for 1-MW Neutron Production},
author = {Stockli, Martin P and Han, Baoxi and Murray, Jr, S N and Pennisi, Terry R and Piller, Chip and Santana, Manuel and Welton, Robert 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- 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- 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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jan 01 00:00:00 EST 2015},
month = {Thu Jan 01 00:00:00 EST 2015}
}

Conference:
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