Transport of long-pulse relativistic electron beams in preformed plasma channels in the ion focus regime

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5412363

Miller, J D

Experiments have been performed demonstrating efficient transport of long-pulse (380 ns), high-current (200 A), relativistic electron beams (REBs) in preformed plasma channels in the ion focus regime (IFR). Plasma channels were created by low-energy (< 300 eV) electron beam ionization of low pressure monatomic gases (Ne, Ar, Kr, and Xe). Experimental results show development of transverse current centroid oscillations with real frequencies and qualitative scaling with the space-charge neutralization fraction, f{sub e}, and channel ion mass, in agreement with theoretical values predicted for the ion hose instability. Microwave emission has also been observed indicative of REB-plasma electron two-stream instability. Plasma channel density measurements indicate that the two-stream instability can become dominant for measured f{sub e} values slightly above unity. The author has introduced a theoretical analysis for high-current REB transport and modulation in axially periodic IFR plasma channels. Analytic expression for the electric field are found for the case of a cosine modulation of the channel ion density. Two different types of channels are considered: (i) periodic beam-induced ionization channels, and (ii) periodic plasma slab channels created by an external source. Analytical conditions are derived for the matched radius of the electron beam and for approximate beam envelope motion using a smooth' approximation. Numerical solutions to the envelope equation show that by changing the wavelength or the amplitude of the space-charge neutralization fraction of the ion channel density modulation, the beam can be made to focus and diverge, or to undergo stable, modulated transport.

• Research Organization: Michigan Univ., Ann Arbor, MI (United States)
• OSTI ID: 5412363
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ELECTRON BEAMS
BEAM TRANSPORT
BEAM CURRENTS
BEAM OPTICS
ELECTRIC FIELDS
FOCUSING
HOSE INSTABILITY
NUMERICAL SOLUTION
PLASMA
PLASMA DENSITY
RELATIVISTIC RANGE
TWO-STREAM INSTABILITY
BEAMS
CURRENTS
ENERGY RANGE
INSTABILITY
LEPTON BEAMS
PARTICLE BEAMS
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PLASMA MICROINSTABILITIES
430200* - Particle Accelerators- Beam Dynamics
Field Calculations
&amp; Ion Optics