Abstracts Brochure - CERN

THPCH159
THPCH160
THPCH161
29-Jun-06 16:00 - 18:00 THPCH — Poster Session
that purpose. We present the main design aspects resulting from the high stability requirement of ELSA. The first
electron spectra measurements show the high level of energy stability achieved. We also present improvements in
the laser injection system leading to a higher transverse stability, a more uniform cathode illumination, and a better
transmission of the whole system.
Analysis of Microphonic Disturbances and Simulation for Feedback Compensation
For FEL projects based on a superconducting
M. Luong, P. Bosland, G. Devanz, E. Jacques (CEA)
linac operating in CW mode, the RF power
optimization finally comes up against the microphonics
disturbances, which result in an unpredictable detuning of the cavities. A new piezoelectric tuner was
developed and mounted on a TTF 9-cell cavity with an appropriate instrumentation. This system enables a full characterization
of the disturbances and the tuner behavior. First measurements were made in a horizontal cryomodule at
4.2 K. They set a basis for simulations to assess the possibility of a feedback compensation, which is usually credited
as impracticable. The outcome of such a compensation is also shown in terms of acceleration voltage amplitude and
phase residual errors.
Theoretical Study and Experimental Result of the RF Coupler Prototypes of Spiral 2
Y. Gómez-Martínez, D. Bondoux, JM. Carretta, J.-M. De Conto, M.
Fruneau, A. Garrigue, D. Marchand, R. Micoud, E. Vernay, F. Vezzu
(LPSC) P. Balleyguier (CEA) M. Di Giacomo (GANIL)
434
Spiral 2 is a 40 MeV superconducting linac
under construction at GANIL. The RF couplers
have to provide a 12 kW CW power to
the cavities at 88 MHz. Two solutions corresponding
to 2 different technologies have
been designed and 2 prototypes have been built. We present the technical proposals and issues as well as the results
(manufacturing, test at low and high power, multipacting. . .) leading to the final choice.
Status of the Polarized Electron Gun at the S-DALINAC
G. Iancu, M. Brunken, J. Enders, H.-D. Gräf, C. Heßler, Y.
Poltoratska, M. Roth (TU Darmstadt) W. Ackermann, W.F.O. Müller,
N. Somjit, B. Steiner, T. Weiland (TEMF) K. Aulenbacher (IKP)
Aiming at an extension of the experimenting
capabilities for nuclear structure physics
at low momentum transfer at the superconducting
Darmstadt electron linear accelerator
S-DALINAC, a polarized electron gun is
being constructed. The new injector will be able to supply the S-DALINAC with 100 keV polarized electrons and
should complement the present, unpolarized thermionic source. The design requirements are a degree of polarization
of at least 80%, a mean current intensity of 0.06 mA and a 3 GHz cw structure. The basic design of the gun was
adapted from the source of polarized electrons at MAMI, Mainz*, and optimized in various simulations. The active
material is a strained layer GaAs crystal which is exposed to an 830 nm pulsed laser beam. We report on the status of
the polarized source, the preparation setup and a test beam line.
*K. Aulenbacher et al., Nucl. Instrum. Meth. A 391, 498 (1997).