Glen R. Lambertson

DYNAMIC DEVICES - PICKUPS AND KICKERS*

A large proportion of the dynamic devices used to interact with the charged‐particle beams in accelerators or storage rings can be classified as pickups or kickers. These devices act through time‐varying electromagnetic fields either to extract information about the particle’s motion or to effect a change in that motion. A given configuration of electrodes may be used either as a pickup or as a kicker; that duality will be addressed in this paper.

Transport of Intense Ion Beams

The possibility of using intense bursts of heavy ions to initiate an inertially confined fusion reaction has stimulated interest in the transport of intense unneutralized heavy ion beams by quadrupole or solenoid systems. We have examined this problem in somne detail, using numerical integration of the coupled envelope equations for the quadrupole case. The general relations which emerge are used to develop examples of high energy transport systems and as a basis for discussing the limitations imposed by a transport system on achievable intensities for initial acceleration.

EXTENDIBLE-ENERGY SYNCHROTRONS.

Abstract Synchrotron guide-field arrangements have been developed that provide for a convinient and economical later increase in energy by the addition of components omitted in the initial construction. Criteria for the design of such an accelerator include new considerations such as emphasis on small circumference to reduce initial costs and on magnet configurations for both stages that have similar orbit behavior and that require little realignment of replacement of the original magnets in the conversion. Space added for future components might also be useful to improve the accelerator in other directions. Thus, at modest cost, the initial layout would afford, in addition to specific provision for conversion to higher energy, a more general flexibility for response to future needs and exploitation of future technology.

Performance of the Bevalac

The performance of the Bevalac is reported. The Bevalac uses the LBL SuperHILAC as the heavy ion injector to the Bevatron. Ion species up to 40A have been accelerated to energies of 1.9 GeV/A at modest intensity. Neon has been accelerated to 2.1 GeV/A at an intensity of 4·1010 particles per pulse. The modifications to the SuperHILAC and Bevatron are briefly reviewed and the computer control system is described. Results of the first phase of operation and plans for further improvements are reported.

The Slotted Coax as a Beam Electrode

The slot coupled TEM line has been employed at CERN as a pick up electrode in the GHz range. It is a compact and broad band device, and will be quite attractive if the coupling efficiency is competitive with an array of quarter wave loops. In this paper, we study various properties of such a structure.

Items from the Construction of ESCAR

ESCAR is an experimental superconducting accelerator which is being built at Lawrence Berkeley Laboratory to gain timely, full-scale experience in the construction and operation of a fully cryogenic accelerator. A report is given of the construction of several non-conventional items.

Feedback to Suppress Beam Insiabiiliiies in Future Proton Rings

Criteria for the design of feedback systems to suppress coherent beam instabilities are presented. These address starting amplitudes, diffusion from noise during damping or long storage, and choice of kicker. As a model for future accelerators, specifications of the proposed 20 leV SSC are used to calculate parameters of systems to control expected instabilities. A scenario and hardware to stabilize the transverse mode-coupling instability is examined. The scale of the systems is large but not out of scale with the large ring.

Recent Experimnts on Forming Electron Rings at Berkeley

In the initial electron-ring experiments with a new high-current, 2 MeV electron injector an efficient method of trapping of the injected beam was developed, and a suitable compression cycle was found in which betatron amplitude growth on single-particle resonances is negligible. The ring behavior is satisfactory during the compression cycle at low intensity (Ne 1012 electrons a longitudinal (negative mass) instability causes particle loss and radial spreading of the electron rings. Increasing the energy spread in the beam has raised the threshold for several phenomena observed in connection with this instability. The effects of changing the electromagnetic environment of the electron rings to suppress this instability are being investigated.

Report of the working group on technology

This paper summarizes the results of the working group on technology at the 1990 Berkeley Conference on beam dynamics of high luminosity asymmetric collider rings. The topics addressed were a conceptual design of the RF system, RF cavity design, a power limit for both cavities and RF windows, beam‐feedback for controlling beam growth, and a new crab cavity design. (AIP)

Intense Antiproton Source for a 20-TeV Collider

The feasibility of producing, collecting and cooling p¿s at a rate > 3.108 s-l is demonstrated. This implies a filling time of ~ 12 hours to reach a luminosity of ¿ 1032cm-2s-1 in the collider.