Plasma studies on a hollow cathode, magnetic multipole ion source for neutral beam injection

Journal Article · Tue Jun 01 00:00:00 EDT 1982 · Rev. Sci. Instrum.; (United States)

DOI:https://doi.org/10.1063/1.1137051· OSTI ID:5553555

Goebel, D M; Forrester, A T

A series of Langmuir probe studies has been undertaken on the hydrogen plasma of an 8 x 8-cm extraction area hollow cathode, magnetic multipole ion source intended for use in neutral beam injection systems. Five movable probes were utilized to measure plasma density, electron temperature, plasma potential, and primary electron density as a function of position in the plasma generator and performance of the ion source. The measurements indicate that at discharge current below 150 A, a fairly uniform plasma over the source volume, with a potential positive with respect to the anode, is generated. The performance of the plasma generator at low currents resembles the filament discharge, magnetic multipole confinement ion source. The ion source in this case has good efficiency and plasma uniformity, but atomic species fractions of less than 70%. As the discharge current is increased, the plasma separates into a high-density, high-ionization, positive potential region near the cathode, and a lower-density, negative potential plasma near the extraction grids. This plasma near the acceleration electrodes is characterized by a relatively low primary electron to plasma electron density ratio of about 2%. The performance of the source significantly increases over the uniform volume plasma case with atomic species output of typically 85% and gas utilization efficiencies of 40%--65%. The high-current, hollow cathode discharge produces a plasma configuration and output performance similar to that of the duoPIGatron ion source, but with lower noise levels.

• Research Organization: Electrical Engineering Department, University of California, Los Angeles, Los Angeles, California 90024
• OSTI ID: 5553555
• Journal Information: Rev. Sci. Instrum.; (United States), Vol. 53:6, Issue 6
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ION SOURCES
BEAM NEUTRALIZATION
EFFICIENCY
ELECTRIC DISCHARGES
ELECTRON DENSITY
ELECTRON TEMPERATURE
EXPERIMENTAL DATA
HOLLOW CATHODES
HYDROGEN
MAGNETIC FIELDS
MULTIPOLAR CONFIGURATIONS
PERFORMANCE
PLASMA
PLASMA DENSITY
SPACE DEPENDENCE
CATHODES
CLOSED CONFIGURATIONS
DATA
ELECTRODES
ELEMENTS
INFORMATION
MAGNETIC FIELD CONFIGURATIONS
NONMETALS
NUMERICAL DATA
430301* - Particle Accelerators- Ion Sources