Self-consistent chaos in the beam-plasma instability
- Stanford Linear Accelerator Center, Menlo Park, CA (United States)
- Colorado Univ., Boulder, CO (United States). Applied Mathematics Program
- Texas Univ., Austin, TX (United States)
The effect of self-consistency on Hamiltonian systems with a large number of degrees-of-freedom is investigated for the beam-plasma instability using the single-wave model of O`Neil, Winfrey, and Malmberg.The single-wave model is reviewed and then rederived within the Hamiltonian context, which leads naturally to canonical action- angle variables. Simulations are performed with a large (10{sup 4}) number of beam particles interacting with the single wave. It is observed that the system relaxes into a time asymptotic periodic state where only a few collective degrees are active; namely, a clump of trapped particles oscillating in a modulated wave, within a uniform chaotic sea with oscillating phase space boundaries. Thus self-consistency is seen to effectively reduce the number of degrees- of-freedom. A simple low degree-of-freedom model is derived that treats the clump as a single macroparticle, interacting with the wave and chaotic sea. The uniform chaotic sea is modeled by a fluid waterbag, where the waterbag boundaries correspond approximately to invariant tori. This low degree-of-freedom model is seen to compare well with the simulation.
- Research Organization:
- Univ. of Texas, Austin, TX (United States). Institute for Fusion Studies
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG05-80ET53088
- OSTI ID:
- 10137801
- Report Number(s):
- DOE/ET/53088-587; IFSR-587; ON: DE93009581
- Resource Relation:
- Other Information: PBD: 8 Feb 1993
- Country of Publication:
- United States
- Language:
- English
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