This story first appeared in Fermilab Today on September 30, 2009.
For the first time, a superconducting radio frequency cavity made by a US manufacturer passed the gradient benchmark required for the proposed International Linear Collider.
Advanced Energy Systems Inc. of Medford, NY, produced the nine-cell niobium cavity, which achieved an acceleration gradient of 41 megavolts per meter, surpassing the 35 megavolts per meter benchmark, during tests earlier this month at Thomas Jefferson National Accelerator Facility in Newport News, Virginia.
The accelerating gradient is a measure of how much an accelerator can increase a particle's energy over a certain distance. Future accelerators, like the ILC, aim to achieve the highest possible gradient to build shorter, and hence cheaper, machines.
AES president Tony Favale said a new treatment process, in which Jefferson Lab baked the cavities at higher temperatures for less time, might have contributed to better results. Baking the cavities removes hydrogen from the niobium.
"They always said our welds were beautiful, but having a beautiful weld doesn't mean it will pass the test," Favale said. "Maybe it's the higher temperatures. We can't wait to see how the next cavities test."
Fermilab, which purchased the cavity from AES, plans to install it in a cryomodule planned for construction in 2010, said Mark Champion, SRF development department head in Fermilab's Technical Division. The proposed ILC will require 16,000 superconducting cavities.
AES has produced 10 cavities so far, eight of which have been processed and tested. The qualifying cavity is the eighth built by AES. The ninth cavity also performed well, topping out just below the benchmark, at 34 megavolts per meter.
"The excellent performance of the latest AES cavity is encouraging," said Bob Kephart, director for Fermilab's ILC program. "It is an important step for US industry to become competitive manufacturers of SRF components."
Three other North American manufacturers—Niowave, of Lansing, Mich., Roark, of Brownsburg, Ind., and PAVAC Industries Inc., of British Columbia, Canada—will provide their first cavities to Fermilab in 2010.
by Chris Knight
