U.S. industry developing SRF cavity expertise

AES recently completed these six Tesla-style cavities.

A new batch of superconducting radio-frequency cavities started to arrive at Fermilab this month, and expectations for their performance are high.

This group of 1.3 gigahertz, or “Tesla style,” cavities marks the third production of its kind for Advanced Energy Systems, a U.S. accelerator technology company based in Medford, New York.  Over the past four years, AES has delivered 10 Tesla-style cavities in two separate batches to Fermilab. This latest batch will bring the total to 16.

AES estimates that Fermilab will have all six new cavities by the end of September.

As each cavity arrives on site, Fermilab conducts a series of measurements to determine if it meets the required specifications. The cavity then undergoes chemical processing at Argonne National Laboratory or Jefferson Lab, followed by a number of tests. If it performs well, it gets integrated into a cooled vessel called a cryomodule to become part of Fermilab’s new SRF test accelerator, currently under construction at the New Muon Laboratory.

The accelerating gradient, or how much the cavity increases a particle’s energy, is the ultimate deciding factor. To make it into Fermilab’s test accelerator, each cavity must have an accelerating gradient of at least 35 megavolts per meter. In the last two years, multiple cavities from AES have met this goal.

John Rathke, chief engineer at AES, attributes the higher accelerating gradients to improvements made during both the manufacturing and chemical treatment process. The company’s purchase of their own electron-beam welding machine allowed AES to improve the mechanical quality and uniformity of the cavities. But Rathke attributes the major jump in performance to improvements made during the treatments done at Fermilab, Argonne and Jefferson Lab.

“It’s an example of AES and the national laboratories getting better all together,” Rathke said.

AES is now starting to manufacture 20 more cavities for Fermilab, a purchase funded by the American Recovery and Reinvestment Act.

-- Elizabeth Clements

New employees - Aug. 30

Hang Yin and Hema Ramamoorthi

Very tiny, very cool

from Science News, Aug. 27, 2010

Annoyingly tiny fridges may not be restricted to hotels or dorm rooms much longer. A new study proposes a way to construct the smallest refrigerator yet, based on just a few particles and capable of cooling to near absolute zero. 

The study, which will appear in an upcoming issue of Physical Review Letters, pushes the limits of how small a cooling device can get and still remain functional.

“When thermodynamics was first invented, it was applied to big, steam engine sorts of things,” says physicist Tony Short of the University of Cambridge in England, who was not involved in the study. “The fact that you can bring the ideas all the way down to individual quantum systems of tiny dimensions and the same basic ideas still work is quite nice.”

Read more