TRANSVERSE ELECTRON-PROTON TWO-STREAM INSTABILITY IN A BUNCHED BEAM
- Tai-Sen F.
- Robert J.
For intense proton beams, the focus of recent two-stream instability analyses has been on the transverse instability observed in the Proton Storage Ring (PSR) at Los Alamos National Laboratory. The PSR stores a long proton bunch with a near triangular line density profile for a duration of about one millisecond. The instability is observed as rapidly growing transverse oscillations of the stored beam, usually occuring when the beam intensity reaches 2.5 x 10{sup 13} ppp or higher, causing fast beam loss. Experimental results support the conjecture that the instability in PSR is due to the two-stream interaction between the circulating proton beam and the electrons created in the ring, i.e., the so called e-p instability. However, the understanding of the physics of this instability is usually based on the theory developed for a continuous beam of uniform line density. Although computer simulations have been implemented or are being developed to study the e-p instability in bunched beams, a companion analytical theory still remains to be developed. The present work is an attempt to investigate the transverse e-p instability in a proton bunch using an analytical approach based on the centroid model built on the 'one-pass' interaction between the protons and the electrons. This paper is an analytical investigation of the transverse electron-proton (e-p) two-stream instability in a proton bunch propagating through a stationary electron background. The equations of motion, including the effect of damping, are derived for the centroids of the proton beam and the electron cloud. An approach is developed to solve the coupled linear centroid equations in the time domain describing the e-p instability in proton bunches with nonuniform line densities. Examples are presented for proton line densities corresponding to uniform and parabolic profiles.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 974710
- Report Number(s):
- LA-UR-01-3024; TRN: US1002371
- Resource Relation:
- Journal Volume: 1; Conference: "Submitted to: 2001 Particle Accelerator Conference, June 18-22, 2001, Chicago."
- Country of Publication:
- United States
- Language:
- English
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