In this paper we have outlined the basic issues important in the design of a Next Linear collider. The energy can be obtained by essentially conventional means, with the use of RF accelerating structures combined with high peak power RF sources -- klystrons -- which are similar to those used presently in the SLC. The key difference is the change of frequency by a factor of 4. For the structures this change of frequency presents no problem. Structures at 11.4 GHz have been constructed; damped and detuned structures have been built or are being designed. The power source is very close to realization. The klystron discussed this paper could easily provide enough power for the lower gradient option. The RF pulse compression necessary to achieve the proper pulse length has been tested and has behaved as theory would indicate. he luminosity of the Next Linear Collider is perhaps the more difficult problem. To reach the desired levels, it is necessary to compress the beam spot to a few hundred square nanometers. This situation is forced upon us by conservation of energy; the wall-plug power must be kept within reasonable bounds. In spite of the small size required, many of themore » tolerance can be brought to conventional values when compensation techniques are applied. The second major component to the luminosity increase is the acceleration of many bunches on each machine cycle. This increases the efficiency of the collider but also introduces many complications throughout all the subsystems. Experience have been gained at the SLC which accelerates three bunches on each cycle, and also at all long- pulse linacs which accelerate sometimes thousands of bunches on each cycle. Thus far, no fundamental problems have been discovered which would preclude the acceleration of trains of bunches.« less

The next linear collider

This paper gives a status report on the conventional approaches to linear colliders at DESY, KEK, SLAC and INP-Protvino in the S- and X-Band regime Critical topics are reviewed and a discussion of global issues such as future R D requirements is included

/pdf/review-of-studies-on-conventional-linear-colliders-in-the-s-3mvjpl50iv.pdf

Review of studies on conventional linear colliders in the S- and X-Band regime

A high-power X-band klystron employing a double-gap output cavity has been operating at SLAC. Multi-gap output circuits have lower surface gradients at the interaction gaps than single-gap ones but are prone to self-oscillate due to negative beam loading and trapped higher-order modes. In the double-gap circuit design, considerable attention had been directed to deal with these stability problems. The performance of the present tube appears to be limited by gap breakdown and beam interception particularly at long pulses. A three-gap output cavity is currently under development to further reduce the gap surface gradient. Another new feature of the circuit is an enlarged downstream drift tube to improve on beam clearance. This paper discusses the considerations involved in designing a multi-gap output cavity and presents the cold test measurements on the three-gap circuit. The experimental data is compared with numerical results from the 3-D simulation code ARGUS.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

/pdf/three-gap-klystron-output-cavity-at-x-band-4eoayxqx9c.pdf

Three-gap klystron output cavity at X-band

W. R. Fowkes, M. A. Allen, R. S. Callin, G. Caryotakis, K. R. Eppley, K. S. Fant, Z. D. Farkas, J. Feinstein, K. Ko, R. F. Koontz, N. Kroll, T. L. Lavine, T. G. Lee, R. H. Miller, C. Pearson, G. Spalek, A. E. Vlieks, and P. B. Wilson Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309, USA

/pdf/rf-power-generation-for-future-linear-colliders-44kvrwxjt7.pdf

RF power generation for future linear colliders

The purpose of this paper is to review the ongoing research at SLAC toward the design of a next-generation linear collider (NLC). The energy of the collider is taken to be 0.5 TeV in the CM with a view towards upgrading to 1.0 TeV. The luminosity is in the range of 10{sup 33} to 10{sup 34} cm{sup {minus}2} sec{sup {minus}1}. The energy is achieved by acceleration with a gradient of about a factor of five higher than SLC, which yields a linear collider approximately twice as long as SLC. The detailed trade-off length and acceleration will be based on total cost. A very broad optimum occurs when the total linear costs equals the total cost of RF power. The luminosity of the linear collider is obtained basically in two ways. First, the cross-sectional area of the beam is decreased primarily by decreasing the vertical size. This creates a flat beam and is useful for controlling beamstrahlung. Secondly, several bunches ({approximately}10) are accelerated on each RF fill in order to more efficiently extract energy from the RF structure. This effectively increases the repetition rate by an order of magnitude. In the next several sections, we trace the beam through the collidermore » to review the research program at SLAC. 41 refs., 1 fig.« less

/pdf/progress-towards-the-design-of-a-next-linear-collider-3x1klkpn0u.pdf

Progress towards the design of a next linear collider

The next generation of linear colliders requires peak power sources of over 200 MW per meter at frequencies above 10 GHz at pulse widths of less than 100 nsec. Several power sources are under active development, including a conventional klystron with rf pulse compression, a relativistic klystron (RK) and a crossed-field amplifier. Power from one of these has energized a 0.5 meter two- section High Gradient Accelerator (HGA) and accelerated a beam at over 80 MeV meter. Results of tests with these experimental devices are presented here.

/pdf/rf-power-sources-for-linear-colliders-3env5z6e2n.pdf

T. Houk

Papers

Rf power sources for linear colliders