Fine-tuning the instruments of acceleration
Some members of the automatic cavity tuning machine international collaboration. Front row, from left: Ruben Carcagno, Fermilab; Toshio Sishido, Hotishi Hayano and Ken Watanabe, KEK. Back row, from left: Guennadi Kreps, DESY; Roger Nehring, Sergey Kotelnikov, Dileep Bhogadi, Andrzej Makulski, Bill Mumper and Jerzy Nogiec, Fermilab; Jan-Hendrik Thie, DESY; Cosmore Sylvester, Fermilab; Alessandro Quadrelli, University of Pisa student; Fred Lewis and Warren Schappert, Fermilab.
Achieving resonance in a scientific collaboration is no small feat, but scientists at Fermilab, DESY and KEK have come together to do exactly that: they've improved the mechanism that keeps superconducting radio frequency cavities in tune.
Members of Fermilab's Technical Division and DESY staff, with financial assistance from KEK, recently built four new tuning machines that set SRF cavities to the correct frequency and alignment. More highly automated than their predecessors, the machines save time and labor and ensure greater consistency in RF cavity quality. They do this by squeezing or stretching individual cells in a nine-cell cavity, allowing all of them to perform identically and impart the same acceleration to the beam.
"Now we don't need RF experts to tune them one by one," said Technical Division Head Giorgio Apollinari. "We can put them in a machine, push a button, and let it run."
The teams engineered the new machines with DESY's future X-ray Free-Electron Laser in mind, as well as the proposed Project X and International Linear Collider. If scientists were to build the ILC, it would need 18,000 SRF cavities, all of which would require tuning.
"You cannot conceive of doing this by hand," Apollinari said.
Under the technical direction of electrical engineer Andrzej Makulski and software architect Jerzy Nogiec, Fermilab TD staff developed a complete set of control electronics and control software for the tuning machines. In Germany, DESY staff developed the mechanical assembly and electrical devices.
-- Leah Hesla