摘要:

We discuss the applications of short, high brightness, high intensity electron bunches to colliders, generators of x‐ray radiation like FELs and Compton backscattering, and high frequency linear accelerators like laser or plasma wakefield accelerators. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50315

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

After reaching the CTF objectives in terms of 30 GHz power production in 1994 the present CTF work focuses on bunch compression studies, photocathode measurements and on the preparation of CTF phase II. An overview of the present CTF experiment and of the future CTF phase II upgrade is given. Achieved CTF performances, first results from magnetic bunch compression and results from quantum efficiency measurements of Cs2Te photocathodes are reported. The design of the S‐band RF Gun and accelerating structures under construction for CTF II is shown. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50298

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report on recent experiments using a magnetic chicane compressor at 8 MeV. Electron bunches at both low (0.1 nC) and high (1 nC) charges were compressed from 10–15 ps to less than 1 ps (FWHM). A transverse deflecting rf cavity was used to measure the bunch length at low charge; the bunch length at high charge was inferred from the induced energy spread of the beam. The longitudinal centrifugal space‐charge force [Phys.Rev.E51, 1453 (1995)] is calculated using a point‐to‐point numerical simulation and is shown not to influence the energy‐spread measurement. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50307

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The production and measurement of short electron and positron bunches in the Stanford Linear Collider (SLC) will be presented in this paper. The bunches are compressed in a transport line between the damping rings and the linac. The electron and positron bunch distributions in the SLC linac have been measured using a Hamamatsu, model N3373‐02, 500‐femtosecond streak camera (1). The distributions were measured at the end of the SLC linac versus the bunch compressor RF voltage. The measurements are compared with simulations. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50320

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

One primary determinant of the quality of the final CEBAF beam is the length of the accelerated bunches. Therefore, many studies on the bunch length have been completed over the years at CEBAF, using both computer simulations and experiment. The main goals of the effort were to quantify the smallest bunch length that could be obtained with the injector and to develop operational settings for the injector. By examining the evolution and distortion of the longitudinal phase space as bunching occurs, it becomes clear that the bunch length is minimized not only when the phase space distribution is oriented without slope (i.e. there is a longitudinal focus and &sgr;56is zero), but also when some of the non‐linearity in the bunching force is systematically corrected by a suitable phasing of the RF cavities producing the bunching. Settings with this property have been established in the CEBAF injector and have yielded phase transfer measurements in beautiful agreement with the calculations. The measurements are clearly precise enough to allow the first‐order non‐linearity to be corrected. A bunch length of 0.35° (at 1497 MHz) has been obtained for low currents at CEBAF. The compression ratio is about 200 in the ‘‘best’’ case and the bunch length is 200 &mgr;m (650 fsec.) ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50330

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Phase space bifurcation has been observed in modeling a CW photocathode free‐electron laser (FEL) injector at CEBAF. We show theoretically and numerically that, in a 3‐dimensional space‐charge‐dominated beam, it originates from those electrons residing in the two wings of the axial density distribution. The underlying mechanism for this kind of phenomenon is that the axial beam density generally is higher in the main part than in the wings of a beam; therefore the main part and the wings experience different amounts of betatron phase shift due to space charge, leading to phase space bifurcation as a crossover occurs during beam propagation. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50291

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

In this paper we discuss how the injector specifications of a 2nd‐generation plasma beat wave accelerator (PBWA) experiment can be achieved by a photo‐injector. Typical required bunch lengths (FWHM) are 50 microns with 15 pC bunch charge. We analyze the possibility of generating such short electron bunches directly from a photoinjector by illuminating a photocathode in an RF electron gun with a phase‐locked 160‐fs laser pulse. In particular, we address all de‐bunching effects taking place during acceleration and transport through the photo‐injector. We provide a set of analytical scaling laws, as well as a comparison with detailed simulations of the beam dynamics. The possible performances of the present SATURNUS linac setup are presented, as well as the anticipated capabilities of a multi‐cell RF gun structure based on the PWT linac presently in operation at UCLA. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50292

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The Next Linear Collider (NLC) being designed at SLAC requires a train of 90 electron bunches 1.4 ns apart at 120 Hz. The intensity and emittance required at the interaction point, and the various machine systems between the injector and the IP determine the beam requirements from the injector. The style of injector chosen for the NLC is driven by the fact that the production of polarized electrons at the IP is a must. Based on the successful operation of the SLC polarized electron source, a similar type of injector with a DC gun and subharmonic bunching system is chosen for the NLC. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50293

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The X‐band linac of the Next Linear Collider (NLC) will accelerate bunches of about 100 &mgr;m rms length to energies of 250–750 GeV. The task of the NLC bunch compressor is to reduce the initial bunch length of 4–5 mm, at extraction from the damping ring, by a factor of 40, to the desired value. This task is accomplished in two separate stages. The first stage at 2 GeV consists of an rf section and a wiggler. The second stage at 10 GeV is formed by an arc, an rf section, and a chicane. The system is designed such that the final bunch phase is insensitive to initial phase errors and to beam‐loading in the intermediate S‐band pre‐linac. Additional decelerating rf sections are employed to compensate significant longitudinal aberrations. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50294

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Methods and limitations on producing very short bunches in linear accelerators have been studied. The use of magnetic compressors as well as the direct application of RF guns are discussed. The coherent synchrotron radiation might be the most import limitation factor. (AIP) ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50326

出版商:AIP    

年代:1996

数据来源: AIP