| Paper | Title | Page |
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| MOP84 | First Cryogenic Tests with JLab's new Upgrade Cavities* | 216 |
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| For the upgrade of CEBAF to 12 GeV two types of 7-cell cavities have been developed: the High Gradient type (HG) has been optimized with respect to the ratio of Epeak/Eacc and for the Low Loss (LL) type the shunt impedance has been maximized. Each cavity type features four DESY type coaxial HOM couplers and a waveguide input coupler. Design goals for these cavities have been set to Eacc = 20 MV/m with a Q-value at 2.05 K of Q0 = 8·109. A niobium prototype of each cavity has been fabricated at JLab and in a first test the HG cavity has been evaluated at cryogenic temperatures after appropriate buffered chemical polishing. Data for Q(E) were taken at several temperatures after R(T) was measured during initial pump down. In addition the pressure sensitivity as well as the Lorentz force detuning were evaluated. The damping of approximately 20 High Order Modes was measured to verify the room temperature data. Measurements on the LL prototype are in progress. We present in this contribution a summary of measured results of tests we performed on the new proposed shapes of the upgrade cavities. | ||
| THP70 | Experimental Study of an 805 MHz Cryomodule for the Rare Isotope Accelerator | 773 |
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The Rare Isotope Accelerator (RIA) driver linac will use superconducting, 805 MHz, 6-cell elliptical cavities with geometric β values of 0.47, 0.61 and 0.81. Each elliptical cavity cryomodule will have four cavities [1]. Room temperature sections between each cryomodule will consist of quadrupole doublets, beam instrumentation, and vacuum systems. Michigan State University (MSU) has designed a compact cryostat that reduces the tunnel cross-section and improves the linac real estate gradient. The cold mass alignment is accomplished with a titanium rail system supported by adjustable nitronic links from the top vacuum plate, and is similar to that used for existing MSU magnet designs. The same concept has also been designed to accommodate the quarter-wave and half-wave resonators with superconducting solenoids used at lower velocity in RIA. Construction of a prototype β=0.47 cryomodule was completed in February 2004 and is presently under test in realistic operating conditions. Experimental results will be presented including: alignment, electromagnetic performance, frequency tuning, cryogenic performance, low-level rf control, and control of microphonics.
[1] “Cryomodule Design for the Rare Isotope Accelerator”, T.L. Grimm, M. Johnson and R.C. York, PAC2003, Portland OR (2003) |