Andrew M. Sessler

LONGITUDINAL RESISTIVE INSTABILITIES OF INTENSE COASTING BEAMS IN PARTICLE ACCELERATORS

The effect of finite resistance in the vacuum-tank walls on the longitudinal stability of an intense beam of particles in an accelerator is investigated theoretically. We show that even if the particle frequency is an increasing function of particle energy, the wall resistance can render the beam unstable against longitudinal bunching. In the absence of frequency spread in the unperturbed beam, the instability occurs with a growth rate that is proportional to (N/{sigma}){sup 1/2}, where N is the number of particles in the beam and {sigma} is the conductivity of the surface material. By means of the Vlasov equation a criterion for beam stability is obtained. In the limit of highly conducting walls the criterion involves the frequency spread in the unperturbed beam, the number of particles N, the beam energy, geometrical properties of the accelerator, but not the conductivity {sigma}. A numerical example presented indicates that certain observations of beam behavior in the MURA 40-Mev-electron accelerator may be related to the phenomenon we investigated.

Characteristics of a high energy μ+μ− collider based on electro‐production of muons

We analyze the design of a high energy μ+μ− collider based on electro‐production of muons. We derive an expression for the luminosity in terms of analytic formulae for the electron‐to‐muon conversion efficiency and the electron beam power on the production target. On the basis of studies of self‐consistent sets of collider parameters under ‘‘realistic’’ (‘‘optimistic’’) assumptions about available technology with beam cooling, we find the luminosity limited to 10−7 cm−2u2009s−1 (1028 cm−2u2009s−1). We also identify major technological innovations that will be required before μ+μ− colliders can offer sufficient luminosity (1030 cm−2u2009s−1) for high energy physics research.

Design of a relativistic klystron two-beam accelerator prototype

We are designing an experiment to study physics, engineering, and costing issues of an extended Relativistic Klystron Two-Beam Accelerator (RK-TBA). The experiment is a prototype for an RK-TBA based microwave power source suitable for driving a 1 TeV linear collider. Major components of the experiment include a 2.5-MV, 1.5-kA electron source, a 11.4-GHz modulator, a bunch compressor, and a 8-m extraction section. The extraction section will be comprised of 4 traveling-wave output structures, each generating about 360 MW of RF power. Induction cells will be used in the extraction section to maintain the average beam energy at 5 MeV. Status of the design is presented.

Plasma compensation effects with relativistic electron beams

It is noted that a sufficiently dense plasma can neutralize the current of a high-energy lepton beam propagating through it. An e/sup +/-e/sup -/ linear collider design with this plasma compensation has been studied and it was found that high luminosities can be obtained without going to the nanometer beam sizes being discussed. The consequence of compensation on B-factory design has also been studied. In particular, the eased constraints on spot size and magnet alignment in the case of a linear collider, and the reduction in beam-beam tune shift for a B-factory are noted. One severe limitation on such a plasma-based device which has not been thoroughly examined is the background due to the interaction of the high-energy beams with the plasma ion nuclei.<<ETX>>

RADIATION FROM FINE, INTENSE, SELF-FOCUSSED BEAMS AT HIGH ENERGY

A theoretical analysis is presented of the radiation emitted when an intense, relativistic, low emittance electron beam propagates through a channel of preionized gas. The beam will self-focus to a small radius and radiate, in the self-induced magnetic field, and it will emit an intense burst of gamma rays. If the beam is subject to a conventional wiggler field, the result will be a “wiggled channel,” and a subsequent pulse of high energy electrons will radiate, more effectively than in the absence of ions, a substantial fraction (≈ 0.1%) of its power coherently as an X-ray laser beam.

Critical issues in low energy muon colliders—a summary

We present a brief summary of the current state of conception and understanding of the accelerator physics issues for low energy muon colliders envisioned as Higgs factories, associated technological challenges and future research directions on this topic.

Critical issues in low energy muon colliders - a summary

Abstract We present a brief summary of the current state of conception and understanding of the accelerator physics issues for low energy muon colliders envisioned as Higgs factories, associated technological challenges and future research directions on this topic.