Experimental studies of multiple electron beam merging, mismatch, and emittance growth in a periodic solenoidal transport channel

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:6973114

Kehne, D M

Experiments performed at the Univ. of Maryland Electron Beam Transport Experiment investigate the merging and transport of multiple beams under matched and mismatched conditions. Theory predicts that, in the presence of nonlinearities, excess field energy associated with nonuniform charge distributions, beam mismatch, or beam offset will be converted to random kinetic energy in the form of emittance. A round solid electron beam of energy 5 keV and current 240 mA is apertured to form a 5-beamlet configuration of 44 mA. This configuration immediately enters a two-solenoid matching section where the degree of mismatch is controlled. The beam propagates through a 36-solenoid periodic (period = 13.6 cm) transport channel. The beam configuration space (x-y) is observed using a movable fluorescent screen and CCD camera system. Using these pictures, the rms-radius can be determined. At the end of the channel, the beam emittance is measured using a slit/pinhole emittance meter. In both the matched and mismatched cases, the beam is seen to merge in less than half a plasma wavelength. The rms-envelope oscillations verify the matched and mismatched conditions. The mismatched oscillations diminish as excess field energy is converted to emittance. A halo of particles consisting of 10%-20% of the beam current forms during the conversion. With regard to beam structure, the experiment agrees well with PIC simulation results using the SHIFT code. Due to the exclusion of the halo from the emittance measurements of the mismatched beam, a low value of measured emittance resulted. The measured matched beam emittance is 20% higher than predicted by simulation and theory. The beams in the matched and mismatched cases appear azimuthally symmetric at the end of the channel. The profiles are characteristic of stationary distributions, though the mismatched beam exhibits remnant mismatch oscillations. Outstanding agreement is achieved between experiment, simulation and theory.

• Research Organization: Maryland Univ., College Park, MD (United States)
• OSTI ID: 6973114
• Country of Publication: United States
• Language: English

Related Subjects

661220* -- Particle Beam Production & Handling
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BEAM DYNAMICS
BEAM EMITTANCE
BEAM OPTICS
BEAM TRANSPORT
BEAM-BEAM INTERACTIONS
BEAMS
DATA
ELECTRON BEAMS
ENERGY RANGE
EXPERIMENTAL DATA
INFORMATION
KEV RANGE
KEV RANGE 01-10
LEPTON BEAMS
NUMERICAL DATA
PARTICLE BEAMS
Ta
Targets-- (1992-)
WAVE PROPAGATION