Showing papers by "J.W. Wang published in 1989"
TL;DR: Relativistic klystron technology is used to extract 290 MW of peak power from an induction linac beam, and to power a short 11.4-GHz high-gradient accelerator to measure rf phase stability, field emission, and the momentum spectrum of an accelerated electron beam.
Abstract: We have used relativistic klystron technology to extract 290 MW of peak power at 11.4 GHz from an induction linac beam, and to power a short 11.4-GHz high-gradient accelerator. We have measured rf phase stability, field emission, and the momentum spectrum of an accelerated electron beam. An average accelerating gradient of 84 MV/m has been achieved with 80 MW of relativistic klystron power.
58 citations
20 Mar 1989
TL;DR: In this article, the authors present a summary of RF breakdown-limited electric fields observed in experimental linac structures at SLAC (Stanford Linear Accelerator Center) and a discussion of how these experiments can be interpreted against the background of existing, yet incomplete, theories.
Abstract: The authors present a summary of RF breakdown-limited electric fields observed in experimental linac structures at SLAC (Stanford Linear Accelerator Center) and a discussion of how these experiments can be interpreted against the background of existing, yet incomplete, theories. The motivation of these studies, begun in 1984, is to determine the maximum accelerating field gradients that can be used safely in future e/sup +or-/ colliders, to contribute to the basic understanding of the RF breakdown mechanism, and to discover whether a special surface treatment can make it possible to supersede the field limits presently attainable room-temperature copper structures. >
32 citations
Proceedings Article•
01 Jan 1989TL;DR: In this paper, the authors investigated the feasibility of using relativistic klystrons as a power source for future high-gradient accelerators, and developed a high-power (500-MW) short-wavelength (2.6-cm) klystron with beam kinetic energy greater than 1 MeV.
Abstract: Experimental work is underway to investigate the feasibility of using relativistic klystrons as a power source for future high-gradient accelerators. The aim is to develop a high-power (500-MW) short-wavelength (2.6-cm) relativistic klystron with beam kinetic energy greater than 1 MeV. Two different relativistic klystron configurations have been built and tested: a high-gain multicavity klystron at 11.4 GHz and a low-gain two-cavity subharmonic buncher driven at 5.7 GHz. In both configurations power is extracted at 11.4 GHz. In order to understand the basic physics issues involved in extracting RF from a high power beam, both a single resonant cavity and a multicell traveling-wave structure were used for energy extraction. A previously reported problem of high-power RF pulse shortening was overcome, and peak RF power levels of 170 MW have been achieved with the RF pulse of the same duration as the beam current pulse. >
11 citations
01 Aug 1989
TL;DR: In this article, a relativistic klystron was used to power a short, 11.4 GHz high-gradient accelerator, achieving peak power levels of 290 MW.
Abstract: Experimental work is now under way by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future high-gradient accelerators. We have learned how to overcome our previously reported problem of high-power rf pulse shortening and have achieved peak rf power levels of 290 MW. We have used the rf from a relativistic klystron to power a short, 11.4-GHz high-gradient accelerator. The measured momentum spectrum of the accelerated electron beam corresponds to an accelerating gradient of 84 MV/m. 5 refs., 7 figs.
5 citations
20 Mar 1989
TL;DR: In this article, preliminary work on accelerator structures for future teraelectronvolt linear colliders which use trains of e/sup +or-// bunches to reach the required luminosity is described.
Abstract: Preliminary work on accelerator structures for future teraelectronvolt linear colliders which use trains of e/sup +or-/ bunches to reach the required luminosity is described. These bunch trains, if not perfectly aligned with respect to the accelerator axis, induce transverse wakefield modes into the structure. Unless they are sufficiently damped, these modes cause cumulative beam deflections and emittance growth. The envisaged structures are disk-loaded waveguides in which the disks are slotted radially into quadrants. Wakefield energy is coupled via the slots and double-ridged waveguides into a lossy region which is external to the accelerator structure. The requirement is that the Q of the HEM/sub 11/ mode be reduced to a value of less than 30. The work done so far includes MAFIA code computations and low-power RF measurements to study the fields. >
5 citations
01 Jan 1989
TL;DR: In this article, a relativistic klystron was used to power a short, 11.4 GHz high-gradient accelerator with a peak power level of 290 MW and measured momentum spectrum of the accelerated electron beam corresponds to an accelerating gradient of 84 MVIm.
Abstract: Experimental work is now under way by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future highgradient accelerators. We have learned how to overcome our previously reported problem of high-power rf pulse shortening and have achieved peak rf power levels of 290 MW. We have used the rf from a relativistic klystron to power a short, 11.4GHz high-gradient accelerator. The measured momentum spectrum of the accelerated electron beam corresponds to an accelerating gradient of 84 MVIm.