• T.M. Bemis, M.H. Lawrence, J.Z. Zhou
  Beam Power Technology, Inc., Chelmsford, MA
• C. Chen
  MIT/PSFC, Cambridge, Massachusetts

Funding: This work was funded in part by the Department of Energy, Grant No. DE-FG02-07ER84910 and Grant No. DE-FG02-95ER40919, and the MIT Deshpande Center for Technological Innovation.

High-brightness space-charge-dominated elliptic electron or ion beams have wide applications in high-power rf sources, particle accelerators, and/or ion implantation. Building upon recent inventions and theoretical studies on the generation and transport of elliptic charged-particle beams, a basic research and development program is being carried out to experimentally demonstrate a high-brightness, space-charge-dominated elliptic electron beam using a non-axisymmetric permanent magnet focusing system and an elliptic electron gun. Results of the design of such an elliptic electron beam system are presented.

• C. Chen, A.E. Brainerd, J.Z. Zhou
  MIT/PSFC, Cambridge, Massachusetts

Funding: This work was supported by the Department of Energy, Grant No. DE-FG02-95ER40919 and the Air Force Office of Scientific Research, Grant No. FA9550-06-1-0269.

Relativistic elliptic electron beams have applications in the research and development of a new class of elliptic- or sheet-beam klystrons which have the potential to outperform conventional klystrons in terms of power, efficiency, and operating voltage. This paper reports on results of a small-signal analysis of space-charge waves on a relativistic elliptic electron beam in a perfectly-conducting beam tunnel. A dispersion relation is derived. A computer code is developed and used in studies of the dispersion characteristics of various relativistic elliptic electron beams.

• J.Z. Zhou, C. Chen, K.R. Samokhvalova
  MIT/PSFC, Cambridge, Massachusetts

Funding: This work was supported by the Department of Energy, Grant No. DE-FG02-95ER40919 and the Air Force Office of Scientific Research, Grant No. FA9550-06-1-0269.

An adiabatic warm-fluid equilibrium theory for a thermal charged-particle beam in an alternating gradient (AG) focusing field is presented. Warm-fluid equilibrium equations are solved in the paraxial approximation and the rms beam envelope equations and the self-consistent Poisson equation, governing the beam density and potential distributions, are derived. The theory predicts that the 4D rms thermal emittance of the beam is conserved, but the 2D rms thermal emittances are not constant. Although the presented rms beam envelope equations have the same form as the previously known rms beam envelope equations, the evolution of the rms emittances in the present theory is given by analytical expressions. The beam density is calculated numerically, and it does not have the simplest elliptical symmetry, but the constant density contours are ellipses whose aspect ratio decreases as the density decreases along the transverse displacement from the beam axis. For high-intensity beams, the beam density profile is flat in the center of the beam and falls off rapidly within a few Debye lengths, and the rate at which the density falls is approximately isotropic in the transverse directions.