Zvyagintsev, V.

Paper	Title	Page
MOP88	RF Coupler Design for the TRIUMF ISAC-II Superconducting Quarter Wave Resonator	228
	R. L. Poirier, K. Fong, P. Harmer, R.E. Laxdal, A.K. Mitra, I. Sekatchev, B. Waraich, V. Zvyagintsev TRIUMF, Vancouver
	An RF Coupler for the ISAC-II medium beta (β=0.058 and 0.071) superconducting quarter wave resonators was designed and tested at TRIUMF. The main goal of this development was to achieve stable operation of superconducting cavities at high acceleration gradients and low thermal load to the helium refrigeration system. The cavities will operate at 6 MV/m acceleration gradient in overcoupled mode at a forward power 200 W at 106 MHz. The overcoupling provides ±20 Hz cavity bandwidth, which improves the stability of the RF control system for fast helium pressure fluctuations, microphonics and environmental noise. Choice of materials, cooling with liquid nitrogen, aluminum nitride RF window and thermal shields insure a small thermal load on the helium refrigeration system by the Coupler. An RF finger contact which causedμdust in the coupler housing was eliminated without any degradation of the coupler performance. RF and thermal calculations, design and test results on the coupler are presented in this paper.
MOP92	Simulation of the RF Coupler for TRIUMF ISAC-II Superconducting Quarter Wave Resonators	234
	V. Zvyagintsev TRIUMF, Vancouver
	The inductive RF coupler for the TRIUMF ISAC-II 106 MHz superconducting accelerating quarter wave resonators was used as a basis for the simulation model of stationary transmission processes of RF power and thermal fluxes. Electromagnetic simulation of the coupler was done with ANSOFT HFSS code. Transmission line theory was used for electromagnetic wave calculations along the drive line to the Coupler. An analogy between electric and thermal processes allows the thermal calculations to be expressed in terms of electrical circuits. The data obtained from the simulation are compared to measured values on the RF coupler.
MOP86	Cold Test Results of the ISAC-II Medium Beta High Gradient Cryomodule	222
	R.E. Laxdal, Y. Bylinskii, G.S. Clark, K. Fong, A.K. Mitra, R. L. Poirier, B. Rawnsley, T. Ries, I. Sekatchev, G. Stanford, V. Zvyagintsev TRIUMF, Vancouver
	Many proposals (RIA, Eurisol, ISAC-II) are emerging for a new generation of high gradient heavy ion accelerators. The ISAC-II medium beta cryomodule represents the first realized application that encorporates many new techniques to improve the performance over machines presently being used for beam delivery. The machine lattice, compatible with multi-charge acceleration, uses high field (9T) superconducting solenoids with bucking coils for active fringe field compensation. The bulk niobium quarter wave medium beta cavity produces 6 MV/m over an effective length of 18cm with a peak surface field of ~30 MV/m. TRIUMF has developed a mechanical tuner capable of both coarse (kHz) and fine (Hz) frequency adjustments of the cavity. The demonstrated tuner resolution is better than 0.1 μm (0.6 Hz). A new rf coupling loop has been developed that operates at 200 Watts forward power with less than 0.5 Watt of power being added to the helium load. Cold alignment in ISAC-II has been done with rf pick-ups using a stretched wire technique. Finally all cryomodule and testing has been done in a clean environment. The alignment cryogenic, solenoid and rf performance will be presented.
	Transparencies
THP13	Construction of a 161 MHz, β=0.16 Superconducting Quarter Wave Resonator with Steering Correction for RIA	626
	A. Facco INFN/LNL, Legnaro, Padova C. Compton, T.L. Grimm, W. Hartung, F. Marti, R.C. York NSCL, East Lansing, Michigan V. Zvyagintsev TRIUMF, Vancouver
	We have built a 161 MHz, β=0.16 superconducting Quarter Wave Resonator with steering correction for the low beta section of RIA. This bulk niobium, double wall cavity, compatible with both separate vacuum between beam line and cryostats or unified one, was designed in collaboration between MSU-NSCL and LNL. The design is suitable for extension to other frequencies, e.g. to obtain the 80 MHz, β=0.085 cavity required in RIA. The shaped drift tube allows correction of the residual QWR steering that can cause emittance growth especially in light ions; this could make this resonator a good alternative to Half-Wave resonators in high intensity proton-deuteron linacs, like the SPES injector project at LNL. First test results will be presented.
THP14	High Beta Cavity Optimization for ISAC-II	627
	R.E. Laxdal, V. Zvyagintsev TRIUMF, Vancouver Z.H. Peng CIAE, Beijing
	The linac for ISAC-II comprises twenty cavities of medium beta (β=5.8 and 7.1%) quarter wave cavities now in the installation phase. A second stage will see the installation of ~20 MV of high beta quarter wave cavities (~10.4%). The cavity structure choice depends on the efficiency of operation, cost, stability, beam dynamics and schedule. Two main cavity types are considered; a low frequency 106 MHz option and a high frequency 141 MHz cavity. We compare and contrast the cavity choices.