New
component design could reduce cost of proposed Facility for Rare Isotope
Beams
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ARGONNE, Ill. (Feb. 8, 2008) — Researchers at the U.S. Department of
Energy's (DOE) Argonne National Laboratory have developed new state-of-the-art
techniques that will lead to significant improvements in the performance of
superconducting niobium cavities. Argonne's superconducting spoke cavities
can operate at lower temperatures and at higher magnetic fields than previous
designs, translating into a potential savings in the cost of a heavy-ion linear
accelerator, such as that required for the proposed Facility for Rare Isotope
Beams (FRIB).
An electromagnetic cavity consists of a space surrounded by an electrical
conductor. When an electromagnetic (EM) wave that shares the cavity's natural
frequency enters, it bounces back and forth within the cavity, creating a phenomenon
known as resonance. As more wave energy enters the cavity, it combines with
and reinforces the standing wave, increasing its intensity and producing very
large EM fields.
Instead of the elliptical superconducting cavities typically used on electron
linear accelerators, Argonne's researchers have turned to "triple-spoke" cavities,
in which three perpendicular niobium pipes intersect the cavity's shell, creating
a region of high acceleration but low surface magnetic field at the center.
This design also offers excellent mechanical stability and good accelerating
efficiency, said Argonne accelerator physicist Michael Kelly, who helped to
develop the cavities.
Development of these superconducting cavities began more than 10 years ago
when DOE first identified the need for a rare isotope beam facility in
the United States. Since then, however, Argonne's physicists and engineers
have developed a number of methods to improve the performance of the cavities.
"By
using electropolishing, high-temperature baking and clean-room assembly techniques,
we were able to significantly boost the capabilities of these cavities," Kelly
said. "Taken as a whole, these techniques have enabled us to reduce
the length of the accelerator by a factor of two or three. Additional improvements
over the next couple of years may further reduce the cost of certain kinds
of accelerators by as much as 20 to 30 percent." The current construction
budget for FRIB totals approximately $550 million dollars.
"New projects such as the proposed rare isotope beam facility would be
prohibitively expensive without the results we are generating from our work,” added
Jerry Nolen, Argonne Distinguished Fellow.
The team of Argonne scientists involved in this project includes Kenneth Shepard,
Petr Ostroumov, Mike Kelly and Jean Delayen, currently of Thomas
Jefferson National Accelerator Facility.
Argonne is one of the sites competing for FRIB, a research facility for
the study of rare isotopes that would revolutionize humanity's understanding
of nuclei, the core of matter and the fuel of stars.
Argonne is collaborating with several national laboratories and universities
on its proposal. Walter Henning, an Argonne Distinguished Fellow who is leading
Argonne's bid, expects DOE's Office of Science to issue a call for proposals
for the rare isotope beams facility in about a month or two with the winning
proposal being selected by the summer. An "Advance Notice" for the
publication in February of a draft proposal request was recently announced
on DOE's website.
If Argonne is selected to build the rare isotope beams facility, conceptual
design could begin in 2009, with the commencement of construction likely by
2011.
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Department of Energy's Office
of Science.
By Jared Sagoff
For more information, please contact Steve McGregor (630/252-5580
or media@anl.gov) at Argonne.
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