Abstracts Brochure - CERN

TUPCH — Poster Session 27-Jun-06 16:00 - 18:00
New Developments for the RF System of the ALBA Storage Ring
ALBA is a 3 GeV, 400 mA, 3rd generation
Synchrotron Light Source that is in the construction
phase in Cerdanyola, Spain. The
RF System will have to provide 3.6 MV of ac-
F. Pérez, B. B. Baricevic, D. Einfeld, H. Hassanzadegan, A. Salom,
P. Sanchez (ALBA)
celerating voltage and restore up to 540 kW of power to the electron beam. For that six RF plants, working at 500 MHz,
are foreseen. The RF plants will include several new developments: 1) DAMPY cavity: the normal conducting HOM
damped cavity developed by BESSY and based in the EU design; six will be installed. 2) CaCo: A cavity combiner
to add the power to two 80 kW IOTs to produce the 160 kW needed for each cavity. 3) WATRAX: A waveguide
transition to coaxial, specially designed to feed the DAMPY cavities due to the geometrical and cooling constrains. 4)
IQ LLRF: The low level RF will be based on the IQ modulation/demodulation technique, both analogue and digital
approach are being pursued. This paper describes the Storage Ring RF System and reports about the status of these
new developments.
Development of a Novel RF Waveguide Vacuum Valve
The development of a novel rf waveguide
vacuum valve is presented. The rf design A. Grudiev (CERN)
is based on the use of TE0n modes of circular
waveguides. In the device, the T·10 01 mode at the input is converted into a mixture of several TE0n modes which
provide low-loss rf power transmission across the vacuum valve gap, these modes are then converted back into the
T·10 01 mode at the output. There are a number of advantages associated with the absence of surface fields in the
region of the valve: 1)Possibility to use commercially available vacuum valves equipped with two specially designed
mode converter sections. 2)No necessity for an rf contact between these two sections. 3)Increased potential for high
power rf transmission. This technology can be used for all frequencies for which vacuum waveguides are used. The
only drawback is that, in rectangular waveguides, mode converters from the operating mode into the T·10 01 mode
and back again are necessary. Experimental results for the 30 GHz valves developed for the CLIC Test Facility 3
(CTF3) are presented showing in particular that the rf power transmission losses are below 1%.
High Gradient Tests of an 88 MHZ RF Cavity for Muon Cooling
The scheme for a Muon Cooling channel developed
at CERN in the frame of Neutrino
Factory studies foresees the use of 44 and 88
MHz cavities operating at a real-estate gra-
C. Rossi, R. Garoby, F. Gerigk, J. Marques Balula, M. Vretenar
(CERN)
dient as high as 4 MV/m. To assess the feasibility of this scheme, including high-gradient operation at relatively
low frequency and the production and handling of high RF peak powers, a test stand was assembled at CERN. It
included an 88 MHz resonator reconstructed from a 114 MHz cavity previously used for lepton acceleration in the
PS, a 2.5 MW final amplifier made out of an old linac unit improved and down-scaled in frequency, and a PS spare
amplifier used as driver stage. After only 160 hours of conditioning the cavity passed the 4 MV/m level, with local
peak surface field in the gap exceeding 25 MV/m (2.4 times the Kilpatrick limit). The gradient was limited by the
amplifier power, the maximum RF peak output power achieved during the tests being 2.65 MW. This paper presents
the results of the tests, including an analysis of field emission from the test cavity, and compares the results with the
experience in conditioning ion linac RF cavities at CERN.
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