Abstracts Brochure - CERN

MOPLS — Poster Session 26-Jun-06 16:00 - 18:00
Experience with a Zero Impedance Vacuum Flange at He − Leak Temperature for ILC
Several tens of thousands of vacuum flanges
will be used in the construction of the ILC. So
the reliability and large scale reproducibility
of these elements are important issue. To
H. Matsumoto, F. Furuta, I.H. Inoue, K. Saito, S.N. Sakamoto, U.K.
Ueno (KEK)
arrive at a standardized vacuum flange, a new design of a unisex flange has been developed. This important
component has to serve in two roles at He-super-leak temperature; both as an rf seal and as a vacuum seal. We
chose the unisex type with a 90-degree sharp edge forming the seal. The design is a modification of the DESY
S-band rectangular waveguide flange. The variation in flatness between the flange and gasket along the inside wall is
within 50 micrometer. This should present zero impedance for a bunched beam and for rf power. The He-super-leak
performance was measured using the "build up method", i.e.the test was carried out for three hours at 2 degrees
Kelvin. The measured He leak rate was below 1·10 -13 Atm*cc/sec for a test flange after three successive tests. We
describe the design concept and the operational experience at various rf frequencies. These span the frequency range
corresponding to warm and cold accelerators.
Characteristics of 45MV/m Superconducting Structures for KEK STF
First 45MV/m superconducting structures
have been designed and fabricated for the Y. Morozumi, F. Furuta, Y. Higashi, T. Higo, T. Saeki, K. Saito (KEK)
STF linac at KEK. The development of proper
surface processing technology enables the structures to reach a theoretical ultimate gradient of nearly 50 MV/m. RF
design and characteristics of the structures will be presented.
Series Test of High Gradient Single-cell Superconducting Cavity for the Establishment of
KEK Recipe
We have performed a series of vertical tests of
single cell Niobium superconducting cavities T. Saeki, F. Furuta (KEK)
at 2 degrees Kelvin. These tests aimed at
establishing the feasibility of reaching an accelerating gradient of 45 MV/m on a routine basis. The cavity profiles
were all of the KEK low loss design and were fabricated from deep drawn Niobium half shells using electron beam
welding. The cavity surface preparation followed an established KEK procedure of high temperature annealing,
centrifugal barrel polishing, light chemical polishing, electropolishing, and finally a high pressure water rinse. Of the
six cavities tested, three exceeded 45 MV/m on the first test. This clearly establishes the feasibility of this gradient. In
this paper we describe these tests and our future program for optimising the surface preparation.
Resonant Kicker System for Head-on-collision Option of Linear Collider
The separation of incoming and outgoing
(electron and positron) beams at the interac- Y. Iwashita (Kyoto ICR)
tion point of a linear collider is investigated
using a resonant kicker system. It should enable head-on-collisions at the interaction point with the use of staggered
passing times for each bunch at certain locations. Magnetic core materials for such a resonant kicker with a frequency
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