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Abstracts Brochure - CERN

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TUPCH — Poster Session 27-Jun-06 16:00 - 18:00<br />

New Developments for the RF System of the ALBA Storage Ring<br />

ALBA is a 3 GeV, 400 mA, 3rd generation<br />

Synchrotron Light Source that is in the construction<br />

phase in Cerdanyola, Spain. The<br />

RF System will have to provide 3.6 MV of ac-<br />

F. Pérez, B. B. Baricevic, D. Einfeld, H. Hassanzadegan, A. Salom,<br />

P. Sanchez (ALBA)<br />

celerating voltage and restore up to 540 kW of power to the electron beam. For that six RF plants, working at 500 MHz,<br />

are foreseen. The RF plants will include several new developments: 1) DAMPY cavity: the normal conducting HOM<br />

damped cavity developed by BESSY and based in the EU design; six will be installed. 2) CaCo: A cavity combiner<br />

to add the power to two 80 kW IOTs to produce the 160 kW needed for each cavity. 3) WATRAX: A waveguide<br />

transition to coaxial, specially designed to feed the DAMPY cavities due to the geometrical and cooling constrains. 4)<br />

IQ LLRF: The low level RF will be based on the IQ modulation/demodulation technique, both analogue and digital<br />

approach are being pursued. This paper describes the Storage Ring RF System and reports about the status of these<br />

new developments.<br />

Development of a Novel RF Waveguide Vacuum Valve<br />

The development of a novel rf waveguide<br />

vacuum valve is presented. The rf design A. Grudiev (<strong>CERN</strong>)<br />

is based on the use of TE0n modes of circular<br />

waveguides. In the device, the T·10 01 mode at the input is converted into a mixture of several TE0n modes which<br />

provide low-loss rf power transmission across the vacuum valve gap, these modes are then converted back into the<br />

T·10 01 mode at the output. There are a number of advantages associated with the absence of surface fields in the<br />

region of the valve: 1)Possibility to use commercially available vacuum valves equipped with two specially designed<br />

mode converter sections. 2)No necessity for an rf contact between these two sections. 3)Increased potential for high<br />

power rf transmission. This technology can be used for all frequencies for which vacuum waveguides are used. The<br />

only drawback is that, in rectangular waveguides, mode converters from the operating mode into the T·10 01 mode<br />

and back again are necessary. Experimental results for the 30 GHz valves developed for the CLIC Test Facility 3<br />

(CTF3) are presented showing in particular that the rf power transmission losses are below 1%.<br />

High Gradient Tests of an 88 MHZ RF Cavity for Muon Cooling<br />

The scheme for a Muon Cooling channel developed<br />

at <strong>CERN</strong> in the frame of Neutrino<br />

Factory studies foresees the use of 44 and 88<br />

MHz cavities operating at a real-estate gra-<br />

C. Rossi, R. Garoby, F. Gerigk, J. Marques Balula, M. Vretenar<br />

(<strong>CERN</strong>)<br />

dient as high as 4 MV/m. To assess the feasibility of this scheme, including high-gradient operation at relatively<br />

low frequency and the production and handling of high RF peak powers, a test stand was assembled at <strong>CERN</strong>. It<br />

included an 88 MHz resonator reconstructed from a 114 MHz cavity previously used for lepton acceleration in the<br />

PS, a 2.5 MW final amplifier made out of an old linac unit improved and down-scaled in frequency, and a PS spare<br />

amplifier used as driver stage. After only 160 hours of conditioning the cavity passed the 4 MV/m level, with local<br />

peak surface field in the gap exceeding 25 MV/m (2.4 times the Kilpatrick limit). The gradient was limited by the<br />

amplifier power, the maximum RF peak output power achieved during the tests being 2.65 MW. This paper presents<br />

the results of the tests, including an analysis of field emission from the test cavity, and compares the results with the<br />

experience in conditioning ion linac RF cavities at <strong>CERN</strong>.<br />

201<br />

TUPCH141<br />

TUPCH142<br />

TUPCH143

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