Large acceptance angle retarding-potential analyzers

Journal Article · Fri May 01 00:00:00 EDT 1981 · Rev. Sci. Instrum.; (United States)

DOI:https://doi.org/10.1063/1.1136655· OSTI ID:6398469

Molvik, A W

Electrostatic retarding-potential gridded analyzers have been used to measure the current and the axial energy distributions of ions escaping along magnetic field lines in the 2XIIB magnetic fusion experiment at Lawrence Livermore National Laboratory (LLNL). Two analyzers are discussed: a large scanning analyzer with a movable entrance aperture that can measure ion losses from a different segment of the plasma diameter on each shot, and a smaller analyzer that mounts in 5-cm-diam. ports. Careful electromagnetic shielding and grounding were necessary in order to reduce spurious signals. Accurate measurements of ion current require grids that attenuate the plasma flow and isolate it from the analyzer grid potentials, several techniques to suppress secondary and primary electrons, and consideration of the space-charge limits as well as techniques to increase these limits. Accurate measurements of ion energy require, in addition, confining large-angle ion orbits within the analyzer by an axial magnetic field, limiting the sweep rate of the ion-repeller grid, and aligning the analyzer so that it is normal to the magnetic field lines. (The analyzers are also used on the Tandem Mirror Experiment, TMX, where the angular acceptance requirements are reduced). The analyzers measure the axial energy, which in 2XIIB and TMX is much greater than the transverse energy. Several pitfalls and their cures are identified in the design, construction, and operation of these analyzers.

• Research Organization: Lawrence Livermore National Laboratory, University of California, Livermore, California 94550
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6398469
• Journal Information: Rev. Sci. Instrum.; (United States), Vol. 52:5
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ELECTROSTATIC ANALYZERS
DESIGN
FABRICATION
ACCURACY
ALIGNMENT
APERTURES
ELECTRIC CURRENTS
ELECTRONS
ENERGY SPECTRA
GRIDS
IONS
MAGNETIC FIELDS
MAGNETIC MIRRORS
NOISE
PLASMA
SECONDARY EMISSION
SIGNALS
SPACE CHARGE
THERMONUCLEAR REACTORS
BEAM ANALYZERS
CHARGED PARTICLES
CURRENTS
ELECTRODES
ELEMENTARY PARTICLES
EMISSION
FERMIONS
LEPTONS
OPEN PLASMA DEVICES
OPENINGS
SPECTRA
THERMONUCLEAR DEVICES
420800* - Engineering- Electronic Circuits & Devices- (-1989)