Abstracts Brochure - CERN

MOPCH — Poster Session 26-Jun-06 16:00 - 18:00
Development of a 704 MHz Elliptical Cavity for Pulsed Proton Linac
Recent developments on high duty cycle high
intensity proton linac have used, in the high S. Chel, P.-E. Bernaudin, P. Bosland, G. Devanz, B. Visentin (CEA)
energy part, the superconducting technology
because is it considered to be advantageous in terms of power consumption, construction cost and beam loss. In the
framework of the European CARE/HIPPI program, we investigate different options to use the same superconducting
technology even in the low energy part of the linac (from 5 MeV to 200 MeV). Different kind of superconducting
structures (CH structures, spoke or elliptical cavities) are necessary to cover this whole energy range. Since the
higher energy part will be equipped with elliptical cavities, we propose a 704 MHz elliptical cavity which could be
advantageously used in the range 80 MeV up to 200 MeV. An optimized design of this cavity for running in pulsed
mode is presented.
A New RF Tuning Method for the End Regions of the IPHI 4-vane RFQ
The 3-MeV High Intensity Proton Injector
(IPHI) RFQ is constituted by the assembly
of three 2-m-long segments. The tuning of
the end regions of such an accelerator with
O. Delferriere, M. Desmons, A. France (CEA) R. Ferdinand
(GANIL)
respect to the quadrupole mode is generally made by machining the thickness of the end plates. The dipole modes are
moved away from the accelerator mode frequency by adding dipole rods and adjusting their length. In the case of the
last IPHI RFQ segment, the tuning range given by possible plate thickness was not sufficient to adjust the frequency
at 352 Mhz without modifying the notch depth, leading to serious engineering problems for the cooling, new thermomechanical
simulations and drawings. To avoid these difficulties, a new way has been investigated by replacing the
end plate thickness adjustment by a "quadrupole rod" length adjustment. These rods are situated between the beam
axis and the dipole rods, and the tuning range is largely increased. The paper will describe this method applied to
the IPHI RFQ and some experimental results obtained on the cold model.
An Innovative Method to Observe RFQ Vanes Motion with Full-scale RF Power and Water
Cooling
The design of high current RFQs is heavily
strained by thermo-mechanical consider- A. France, O. Piquet (CEA) R. Ferdinand (GANIL)
ations, which eventually have an impact on
machining costs, cooling systems, etc. A 1-meter long copper prototype of the SPIRAL2 RFQ has been specifically
built to corroborate design options. An innovative method has been developed, allowing real-time observation of
mechanical deformations of RFQ vanes, with full-scale RF power and water cooling. Digital images are acquired by a
CCD camera, and processed by a dedicated software. Processing includes contrast stretching, low-pass filtering, and
block-correlation followed by interpolation. Sub-pixel relative motions of RFQ electrode ends are clearly detected and
measured, with RMS errors of the order of 0.6 microns.
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