Neutron Sciences 2008 Annual Report - 17.79 MB - Spallation ...

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FACILITY DEVELOPMENT 2008 ANNUAL REPORT
ORNL NEUTRON SCIENCES neutrons.ornl.gov
Future Initiatives
SNS Power Upgrade and Second Target Station
SNS was designed from the beginning to be
upgraded in power and to accommodate a
second target station to expand the science
capabilities of the complex.
High-density hydrogen operation
of the helicon ion source.
Booster Shot for SNS Ion Source
To improve the performance of the neutron source,
a power upgrade project is in the works that will
increase the beam energy by 30% from 1.0 to 1.3
gigaelectronvolt. The project is awaiting approval to
begin planning and preliminary engineering. Construction
is expected to start in 2012.
An advanced concept for space propulsion could help double the scientific capability of SNS.
When the beam power of the SNS linear accelerator reaches the design limit of 1.4 megawatts (MW), the beam current will be 38 milliamps.
However, plans are to double the beam power to 3 MW by 2011 to help double the facility’s scientific capability. To meet the requirements of a 3-MW neutron
source, the ion beam current must be increased from 38 to 59 milliamps.
One approach to meeting this requirement is being pursued by a team of scientists from SNS and ORNL’s Fusion Energy Division. The researchers are developing
a new hybrid ion source based on a helicon plasma generator developed by the National Aeronautics and Space Administration (NASA) for the variable specific
impulse magnetoplasma rocket (VASIMR), an advanced concept for electric space propulsion. NASA plans to test the technology on the International Space Station
and possibly use it to propel manned spacecraft in the future.
By combining this high-efficiency plasma generator with the existing SNS ion source, developed by Lawrence Berkeley National Laboratory, the researchers
hope to achieve higher beam currents than can be produced from conventional ion sources. The team has constructed a dedicated test facility capable of both
plasma density and beam extraction measurements. Rob Welton, Rick Goulding, Dennis Sparks, Stan Forrester, and Danny Crisp delivered their first success early
on. “We have already achieved much higher plasma densities than produced in typical radiofrequency-driven, negative hydrogen ion sources,” Welton says. “As a
starting point, we have recently extracted about 10 milliamps from this hybrid source by employing a modified magnetic configuration. Our main challenge now is
to increase this beam current to the required 59 milliamps by adding cesium and reconfiguring the magnetic fields to best convert this record plasma density into
usable beam.”
This research promises to benefit fields beyond neutron scattering. “Because these characteristics are desirable in a generator used to create neutral beams for
heating fusion plasma, the low power densities and neutral pressures present in the plasma generator could make the device of interest to the managers of the
ITER [International Thermonuclear Experimental Reactor] fusion experiment,” Goulding says. “Our findings are likely to advance the field of ion source development
for advanced accelerators, ion implantation, and medical isotope production.”
Contact: Martin Stockli (stockli@ornl.gov)