2011 Particle Accelerator Conference - List of Authors (Stockli, M.P.)

Paper	Title	Page
WEP038	Physics Design of a Prototype 2-Solenoid LEBT for the SNS Injector	1564
	B. Han, D.J. Newland ORNL RAD, Oak Ridge, Tennessee, USA T. Hunter, M.P. Stockli ORNL, Oak Ridge, Tennessee, USA
	To mitigate the operational risks associated with the SNS electrostatic LEBT, an R&D effort is underway to develop a 2-solenoid magnetic LEBT, which should improve the reliability while matching or exceeding the beam dynamic capabilities of the present electrostatic LEBT. This paper discusses the physics design of a prototype 2-solenoid magnetic LEBT.

WEP254	Simulation of H⁻ Beam Chopping in a Solenoid-Based Low-Energy Beam Transport (LEBT)	1957
	D.T. Abell, D.L. Bruhwiler, Y. Choi, S. Mahalingam, P. Stoltz Tech-X, Boulder, Colorado, USA B. Han ORNL RAD, Oak Ridge, Tennessee, USA M.P. Stockli ORNL, Oak Ridge, Tennessee, USA
	Funding: This work is supported by the US DOE Office of Science, Office of Basic Energy Sciences, including grant No. DE-SC0000844. The H^- linac for the Spallation Neutron Source (SNS) includes an electrostatic low-energy beam transport (LEBT) subsystem. The ion source group at SNS is developing a solenoid-based LEBT, which will include MHz frequency chopping of the partly-neutralized, 65~keV, 60~mA H^- beam. Particle-in-cell (PIC) simulations using the parallel VORPAL framework are being used to explore the possibility of beam instabilities caused by the cloud of neutralizing ions generated from the background gas, or by other dynamical processes that could increase the emittance of the H^- beam before it enters the radio-frequency quadrupole (RFQ) accelerator.

WEP273	Saddle RF Antenna H⁻ Ion Source Progress	1987
	V.G. Dudnikov, R.P. Johnson Muons, Inc, Batavia, USA S. Murray, T.R. Pennisi, M. Santana, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA
	Funding: Supported in part by USDOE Contract DE-AC05-00OR22725 and STTR Grant DE-SC0002690 In this project we are developing an RF H⁻ surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with a small AlN test chamber and different antennasandmagneticfieldconfigurationsweretestedin the SNS ion source Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H⁻ beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma source (TPS) has been designed. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing.

WEP275	Highly-Persistent SNS H⁻ Source Fueling 1-MW Beams with 7-9 kC Service Cycles	1993
	M.P. Stockli, T.W. Hardek, Y.W. Kang, S.N. Murray, T.R. Pennisi, M.F. Piller, M. Santana, R.F. Welton ORNL, Oak Ridge, Tennessee, USA B. Han ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. Running routinely with ~40-mA, 1-MW beams, the SNS linac is fed from the ion source with ~1ms long, ~50-mA H⁻ beam pulses at 60 Hz. This requires the daily extraction of ~230 C of H⁻ ions, which exceeds the routine daily production of other H⁻ accelerator sources by almost an order of magnitude. The source service cycle has been extended from 2, to 3, to 4, and up to 5.6 weeks without age-related failures. The 7-9 kC of H⁻ ions delivered in single service cycles exceed the service cycle yields of other accelerator sources. The paper discusses the findings as well as the issues and their mitigations, which enabled the simultaneous increase of the beam current, the duty factor, the availability, and the service cycle.

Paper

Title

Page

Physics Design of a Prototype 2-Solenoid LEBT for the SNS Injector

1564

B. Han, D.J. Newland
ORNL RAD, Oak Ridge, Tennessee, USA
T. Hunter, M.P. Stockli
ORNL, Oak Ridge, Tennessee, USA

To mitigate the operational risks associated with the SNS electrostatic LEBT, an R&D effort is underway to develop a 2-solenoid magnetic LEBT, which should improve the reliability while matching or exceeding the beam dynamic capabilities of the present electrostatic LEBT. This paper discusses the physics design of a prototype 2-solenoid magnetic LEBT.

WEP254

Simulation of H⁻ Beam Chopping in a Solenoid-Based Low-Energy Beam Transport (LEBT)

1957

D.T. Abell, D.L. Bruhwiler, Y. Choi, S. Mahalingam, P. Stoltz
Tech-X, Boulder, Colorado, USA
B. Han
ORNL RAD, Oak Ridge, Tennessee, USA
M.P. Stockli
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is supported by the US DOE Office of Science, Office of Basic Energy Sciences, including grant No. DE-SC0000844.
The H^- linac for the Spallation Neutron Source (SNS) includes an electrostatic low-energy beam transport (LEBT) subsystem. The ion source group at SNS is developing a solenoid-based LEBT, which will include MHz frequency chopping of the partly-neutralized, 65~keV, 60~mA H^- beam. Particle-in-cell (PIC) simulations using the parallel VORPAL framework are being used to explore the possibility of beam instabilities caused by the cloud of neutralizing ions generated from the background gas, or by other dynamical processes that could increase the emittance of the H^- beam before it enters the radio-frequency quadrupole (RFQ) accelerator.

WEP273

Saddle RF Antenna H⁻ Ion Source Progress

1987

V.G. Dudnikov, R.P. Johnson
Muons, Inc, Batavia, USA
S. Murray, T.R. Pennisi, M. Santana, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA

Funding: Supported in part by USDOE Contract DE-AC05-00OR22725 and STTR Grant DE-SC0002690
In this project we are developing an RF H⁻ surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with a small AlN test chamber and different antennasandmagneticfieldconfigurationsweretestedin the SNS ion source Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H⁻ beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma source (TPS) has been designed. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing.

WEP275

Highly-Persistent SNS H⁻ Source Fueling 1-MW Beams with 7-9 kC Service Cycles

1993

M.P. Stockli, T.W. Hardek, Y.W. Kang, S.N. Murray, T.R. Pennisi, M.F. Piller, M. Santana, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA
B. Han
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Running routinely with ~40-mA, 1-MW beams, the SNS linac is fed from the ion source with ~1ms long, ~50-mA H⁻ beam pulses at 60 Hz. This requires the daily extraction of ~230 C of H⁻ ions, which exceeds the routine daily production of other H⁻ accelerator sources by almost an order of magnitude. The source service cycle has been extended from 2, to 3, to 4, and up to 5.6 weeks without age-related failures. The 7-9 kC of H⁻ ions delivered in single service cycles exceed the service cycle yields of other accelerator sources. The paper discusses the findings as well as the issues and their mitigations, which enabled the simultaneous increase of the beam current, the duty factor, the availability, and the service cycle.