Laxdal, R.E.

Paper	Title	Page
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
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.
MOP89	A Wire Position Monitor System for the ISAC-II Cryomodule Components Alignment	231
	B. Rawnsley, Y. Bylinskii, G. Dutto, K. Fong, R.E. Laxdal, T. Ries TRIUMF, Vancouver D. Giove INFN/LASA, Segrate (MI)
	TRIUMF is developing ISAC-II, a superconducting (SC) linac. It will comprise 9 cryomodules with a total of 48 niobium cavities and 12 SC solenoids. They must remain aligned at liquid He temperatures: cavities to ±400 μm and solenoids to ±200 μm after a vertical contraction of ~4 mm. A wire position monitor (WPM) system based on a TESLA design has been developed, built, and tested with a prototype cryomodule. The system is based on the measurement of signals induced in pickups by a 215 MHz signal carried by a wire through the WPMs. The wire is stretched between the warm tank walls parallel to the beam axis providing a position reference. The sensors, one per cavity and two per solenoid, are attached to the cold elements to monitor their motion during pre-alignment, pumping and cool down. A WPM consists of four 50 Ω striplines spaced 90° apart. A GaAs multiplexer scans the WPMs and a Bergoz card converts the RF signals to DC X and Y voltages. National Instruments I/O cards read the DC signals. The data acquisition is based on a PC running LabVIEW. System accuracy is ~7 μm. The paper describes system design, WPM calibration and test results.
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.
THP16	Engineering and Cryogenic Testing of the ISAC-II Medium Beta Cryomodule	630
	G. Stanford, Y. Bylinskii, R.E. Laxdal, B. Rawnsley, T. Ries, I. Sekatchev TRIUMF, Vancouver
	The medium beta section of the ISAC-II Heavy Ion Accelerator consists of five cryomodules each containing four quarter wave bulk niobium resonators and one superconducting solenoid. A prototype cryomodule has been designed and assembled at TRIUMF. The cryomodule vacuum space contains a mu-metal shield, an LN2 cooled, copper, thermal shield, plus the cold mass and support system. This paper will describe the design goals, engineering choices and fabrication and assembly techniques as well as report the results of the initial cold tests. In particular we will summarize the alignment procedure and the results from the wire position monitoring system.