Status of X-band standing wave structure studies at SLAC

Dolgashev, Valery; Adolphsen, C.; Burke, D. L.; Bowden, Gordon; Jones, R. M.; Lewandowski, James; Li, Z.; Loewen, R.J.; Miller, R.H.; Ng, C.; Pearson, C.; Ruth, Ronald D.; Tantawi, Sami; Wang, J.W.; Wilson, Perry B.

doi:10.1109/pac.2003.1289673

Cited by 8 publications

(15 citation statements)

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“…These will employ one of the mode launchers to feed rf power into a SW structure. Fields in the middle cell of the SW structure are similar to fields of a large-aperture SW structure already tested at high power (structure SW20a565 [3]). Fields in the other two cells are designed to be at most one half of the middle cell fields, so breakdowns will likely occur in the middle cell.…”

Section: Motivationmentioning

confidence: 55%

“…Since breakdown behavior in TW structures and SW structures is different [3,5], to study this difference and effect of SW cell shape on breakdown, we will perform single cell SW experiments. These will employ one of the mode launchers to feed rf power into a SW structure.…”

Section: Motivationmentioning

confidence: 99%

“…For example, working gradients in specialized small cavities are usually much higher than in high power waveguides and practical accelerating structures. To date, dozens of full-scale travelling wave (TW) structures [1,2] and standing wave (SW) structures [3] have been tested at SLAC in an effort to produce accelerating structures that satisfy NLC/GLC requirements on gradient and breakdown rate. The requirements were met mainly by reducing length of a structure.…”

Section: Introductionmentioning

confidence: 99%

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Travelling Wave and Standing Wave Single Cell High Gradient Tests

Dolgashev¹

2004

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Accelerating gradient is one of the crucial parameters affecting design, construction and cost of next-generation linear accelerators. Operating accelerating gradient in normal conducting accelerating structures is limited by rf breakdown. In this paper we describe an experimental setup for study of these limits for 11.4 GHz travelingwave and standing-wave accelerating structures. The setup uses matched mode converters that launch the circular TM 01 mode into short test structures. The test structures are designed so that the electromagnetic fields in one cell mimic the fields in prototype structures for the Next Linear Collider. Fields elsewhere in the test structures and in the mode converters are significantly lower than in this single cell. This setup allows economic testing of different cell geometries, cell materials and preparation techniques with short turn around time. Here we present design considerations and describe planned experiments.

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Section: Motivationmentioning

confidence: 55%

Section: Motivationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Travelling Wave and Standing Wave Single Cell High Gradient Tests

Dolgashev¹

2004

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“…To explore this possibility, we built several 15-cell π-mode structures for evaluation. In all, four pairs of SW structures were tested [11] : two pairs of a/λ = 0.18 structures, one pair of higher a/λ structures and one pair of lower a/λ structures; these different a/λ designs would be used to produce piece-wise detuning of the dipole modes. Each pair of structures is fed from a high power 3db hybrid with a 90-degree phase difference in order to cancel the transient reflection back to the power source.…”

Section: Standing Wave Optionmentioning

confidence: 99%

Accelerator Structure Development for NLC/GLC

Wang¹

2004

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The NLC (Next Linear Collider) and GLC (Global Linear Collider) [1,2] are e + e -linear collider proposals based on room-temperature accelerator technology -so called "warm machines" in comparison with the TESLA "cold machine" that is based on superconducting accelerator technology. There have been two major challenges in developing X-band (11.4 GHz) accelerator structures for the GLC/NLC. The first is to demonstrate stable, long-term operation at the high gradient (65 MV/m) that is required to optimize the machine cost. The second is to strongly suppress the beam induced long-range wakefields, which is required to achieve high luminosity. The development of high gradient structures has been a high priority in recent years. Nearly thirty X-band structures with various rf parameters, cavity shapes and coupler types have been fabricated and tested since 2000. This program has been a successful collaborative effort among groups at SLAC, KEK, FNAL and other labs. A summary of the main achievements and experiences are presented in this paper as well as a status report on the structure design, high power performance, manufacturing techniques, and other structure related issues.

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“…Another test will be of standing-wave structures with rounded-edged couplers. Earlier versions were limited to about 60 MV/m gradients, which may have been the result of their sharpedged couplers [6].…”

Section: Nlc/glc Summary and Outlookmentioning

confidence: 99%

Normal-conducting rf structure test facilities and results

Adolphsen

Proceedings of the 2003 Bipolar/BiCMOS Circuits and Technology Meeting (IEEE Cat. No.03CH37440)

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The designs for a next-generation linear collider based on normal-conducting rf structures require operation at gradients much higher than those in existing linacs. For the NLC/GLC 11.4-GHz structures, the design unloaded gradient is 65 MV/m, which is about four times that of the 2.9-GHz SLAC Linac. For the CLIC 30-GHz structures, a substantially higher gradient, 170 MV/m, is required. Both the NLC/GLC and CLIC groups are aggressively pursuing programs to develop structures that operate reliably at these gradients and also have acceptable efficiencies and transverse wakefields. Much progress has been made in the past few years, and this paper reviews the programs, test facilities and results from this research. Conference, Portland, Oregon, May 12-16, 2003 * Work supported by Department of Energy contract DE-AC03-76SF00515. Expanded version of paper presented at the 2003 Particle Accelerator NORMAL-CONDUCTING RF STRUCTURE TEST FACILITIES AND RESULTS *C. Adolphsen Stanford Linear Accelerator Center, Stanford University, Stanford CA 94309 USA AbstractThe designs for a next-generation linear collider based on normal-conducting rf structures require operation at gradients much higher than those in existing linacs. For the NLC/GLC 11.4-GHz structures, the design unloaded gradient is 65 MV/m, which is about four times that of the 2.9-GHz SLAC Linac. For the CLIC 30-GHz structures, a substantially higher gradient, 170 MV/m, is required. Both the NLC/GLC and CLIC groups are aggressively pursuing programs to develop structures that operate reliably at these gradients and also have acceptable efficiencies and transverse wakefields. Much progress has been made in the past few years, and this paper reviews the programs, test facilities and results from this research.

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Status of X-band standing wave structure studies at SLAC

Cited by 8 publications

References 1 publication

Travelling Wave and Standing Wave Single Cell High Gradient Tests

Travelling Wave and Standing Wave Single Cell High Gradient Tests

Accelerator Structure Development for NLC/GLC

Normal-conducting rf structure test facilities and results

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