摘要:

The kinetic theory is developed to investigate a conditioner for a helically transported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the contitioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron’s relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one‐third of its initial value.

ISSN:0094-243X    

DOI:10.1063/1.44094

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

This paper presents a new formalism which makes the analysis and understanding of both the relativistic klystron (RK) and the standing‐wave free‐electron laser (SWFEL) two‐beam accelerator (TBA) available to a wide audience of accelerator physicists. A ‘‘coupling impedance’’ for both the RK and SWFEWL is introduced, which can include realistic cavity features, such as beam and vacuum ports, in a simple manner. The RK and SWFEL macroparticle equations, which govern the energy and phase evolution of successive bunches in the beam, are of identical form, differing only by multiplicative factors. Expressions are derived for the phase and amplitude sensitivities of the TBA schemes to errors (shot‐to‐shot jitter) in current and energy. The analysis allows, for the first time, relative comparisons of the RK and the SWFEL TBAs.

ISSN:0094-243X    

DOI:10.1063/1.44095

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A standing‐wave free‐electron laser (SWFEL) has been proposed for use in a two‐beam accelerator (TBA). We modify the previous one‐dimensional discrete cavity model of the SWFEL by introducing drifts between cavities. We also vary the input beam energy as a function of the bunch number. In this new model, we obtain a stable equilibrium solution for a well‐bunched beam (even after inluding all nonlinear terms). We obtain analytic expressions characterizing this equilibrium in the limit of small cavity lengths. We study the dependence of fluctuations in signal phase along the device as a function of detuning, input beam energy, beam length, current errors, and initial signal field amplitude. We are able to find an optimized set of parameters for which the output energy changes by less than 3% across the cavities for a 1% detuning. The maximum change in signal phase is less than 0.12 radians.

ISSN:0094-243X    

DOI:10.1063/1.44096

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We describe a means of producing at train of 40 kA pulses of 3 ps duration as the drive beam for CLIC using an RF–linac driven free electron laser (FEL) buncher. Potential debunching effecs are discussed. Finally we describe a low energy test experiment.

ISSN:0094-243X    

DOI:10.1063/1.44098

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Advanced research on near‐field acceleration, by the time of this meeting, has progressed into mature field of both experimental and theoretical investigation. This field has a number of subcomponents; a few of the more notable are wake‐field acceleration, open structure laser acceleration, and novel rf structures. This paper will provide an overview of these subjects, and examine the most recent advances in near‐field acceleration and the facilities developed for its study, as reported at the Port Jefferson workshop.

ISSN:0094-243X    

DOI:10.1063/1.44088

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We introduce a new accelerator cavity design based on Photonic Band Gap (PBG) structures. The PBG cavity consists of a two‐dimensional periodic array of high dielectric, low loss cylinders with a single removal defect, bounded on top and bottom by conducting sheets. We present the results of both numerical simulations and experimental measurements on the PBG cavity.

ISSN:0094-243X    

DOI:10.1063/1.44089

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We examine some properties of a new type of open accelerating structure. It consists of a series of rectangular cavities, which we call foxholes, joined by a beam channel. The power for accelerating the particles comes from an external radiation source and enters the cavities through their open upper surfaces. Analytic and computer calculations are presented showing that the foxhole is a suitable structure for accelerating relativistic electrons.

ISSN:0094-243X    

DOI:10.1063/1.44091

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The present status of research and development for high‐gradient linacs required for future linear colliders is decribed. The interval of RF frequency considered here ranges from about 10 GHz to 30 GHz and many studies made for NLC (Next Linear Collider) proposed at SLAC, KEK, and IHEP as well as for CLIC (CERN LInear Collider) are covered. After a brief recall of the reason for operating at high frequency when high accelerating gradient is required, major issues are addressed. Effects of strong wake fields on the energy spread at the linac exit and on transverse beam stability, as well as possible compensations are summarized. Consequences for multibunch dynamics are also discussed, together with suggested remedies. The difficult question of the alignment tolerances is approached to underline the necessity of a very efficient scheme of trajectory correction, and the state of the art in building accelerating structure prototypes is given. Prospects for microwave klystrons as high‐power RF sources for normal‐conducting electron and positron linacs in NLC are briefly described. Finally, recent results concerning the CLIC scheme for generating the necessary power, based on a two‐stage accelerator, are presented.

ISSN:0094-243X    

DOI:10.1063/1.44099

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

In this paper we will review recent activities in the area of code development as it affects the accelerator community. We will first discuss the changing computing environment. We will review how the computing environment has changed in the last 10 years, with emphasis on computing power, operating systems, computer languages, graphics standards, and massively parallel processing. Then we will discuss recent code development activities in the areas of electromagnetics codes and beam dynamics codes.

ISSN:0094-243X    

DOI:10.1063/1.44100

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

This report describes the accomplishments of the Working Group on Far Field Accelerators. In addition to hearing presentations of current research, the group produced designs for ‘‘100 MeV’’ demonstration accelerators, ‘‘1 GeV’’ conceptual accelerators and a small electron beam source. Two of the ‘‘100 MeV’’ designs, an Inverse Free Electron Laser (IFEL) and an Inverse Cˇerenkov Accelerator (ICA), use the CO2laser and the 50 MeV linac at the Advanced Test Facility (ATF) at Brookhaven National Laboratory (BNL), requiring only modest changes in the current experimental setups. By upgrading the laser, an ICA design demonstrated 1 GeV acceleration in a gas cell about 50 cm in length. For high average power accelerators, examples based on the IFEL concept were also produced utilizing accelerators driven by high average power FELs. The Working Group also designed a small electron beam source based on the inverse electron cyclotron resonance concept. Accelerators based on the IFEL and ICA may be the first to achieve ‘‘100 MeV’’ and ‘‘1 GeV’’ energy gain demonstration with high accelerating gradients.

ISSN:0094-243X    

DOI:10.1063/1.44101

出版商:AIP    

年代:1992

数据来源: AIP