Abstracts Brochure - CERN

WEPLS — Poster Session 28-Jun-06 16:00 - 18:00
Experiments with Electron Clouds and Sources
The Penning-Malmberg trap ELTRAP installed
at University of Milano can provide
electron clouds of several sizes for study of
non-linear physics: length ranges from 0.15
M. Cavenago (INFN/LNL) G. Bettega, F. Cavaliere, D. Ghezzi, A.
Illiberi, R. Pozzoli, M. Rome (INFN-Milano)
to 1 m, while diameter is varied between 25 mm and 70 mm by changing the electron source: filament or planar
spiral. Vortices develop both in trapped and flowing electron beams. Slow instabilities, due to the accumulation of
ions inside the trap are observed and cured by clearing fields. Results as a function of plasma size are described. Plan
to install a third laser modulated electron source and additional diagnostic are also summarized.
Dark Current Investigation of TTF and PITZ RF Guns
The dark current is one of the limiting factor
in the operation of RF guns at high gradient.
The continuous request of higher brilliance
sources and further emittance minimization,
L. Monaco, P. Michelato, C. Pagani, D. Sertore (INFN/LASA) J.H.
Han, S. Schreiber (DESY) M. Krasilnikov (DESY Zeuthen)
leads to apply higher gradients in the RF gun cavity, with the consequence of a significant dark current production.
In this context we set up a collaborative effort to identify the dark current sources in the gun, in order to discriminate
between the gun and cathode contribution. A critical analysis and organization of dark current measurements,
taken during the operation of TTF and PITZ guns, with several cathodes operated at different accelerating fields
and solenoids focusing, is presented. Potential areas of improvement are also discussed, together with a possible
associated program.
High QE Photocathode at VUV-FEL/TFF
The RF gun-based photoinjector of the VUV-
FEL/TTF at DESY continues to use high
quantum efficiency (QE) photocathodes produced
at LASA, Milano. To study the photo-
D. Sertore, P. Michelato, L. Monaco, C. Pagani (INFN/LASA) J.H.
Han, S. Schreiber (DESY)
cathode behavior during beam operation, an online QE monitoring tool has been installed. In this paper, we present
the hardware and software setup for the online QE measurement and the results so far obtained. The measured QEs
are usually higher than at TTF phase 1. We compare the QE values taken in the RF gun with data measured just after
production with a continuous UV light source.
RF Design of a Cartridge-type Photocathode RF Gun in S-band Linac
A cartridge-type photocathode RF gun is
under development in collaboration with
SPring-8 and Hamamatsu Photonics. Each
type of cathode (Cs2Te, Mg, diamond, Ag-
Cs-O) is sealed in a cartridge-type vacuum
H. Moritani, Y. Muroya, A. Sakumi, T. Ueda, M. Uesaka (UTNL)
H. Hanaki, N. Kumagai, S. Suzuki, H. Tomizawa (JASRI/SPring-8)
J. Sasabe (Hamamatsu Photonics K.K.) J.U. Urakawa (KEK)
tube. Several tubes can be installed in a vacuum chamber. The cathode in the tube is inserted into a center hole in the
back plate of the RF gun by a vacuum manipulator. These cartridge-type photocathodes with high QE or sensitivity
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