Accession Number : ADA184456

Title :   Laser Induced Fluorescent Study of Relativistic Electron Beams.

Descriptive Note : Final rept. 28 Apr 83-31 Jan 86,

Corporate Author : HY-TECH RESEARCH CORP RADFORD VA

Personal Author(s) : Yadlowsky,Edward J ; Hazelton,Robert C

PDF Url : ADA184456

Report Date : Jun 1987

Pagination or Media Count : 69

Abstract : The magnetic fields associated with a relativistic electron beam propagating in a gas provide information about the net current distribution in the beam and the stability of the beam with respect to hose, hollowing, and flute instabilities. In principle, these magnetic fields can be measured using Faraday rotation techniques, or by measuring the Zeeman splitting of atomic/ionic transitions using emission spectroscopy. This work investigates the measurement of magnetic field contours by optically pumping atoms/ions with a narrow band dye laser tuned to a Zeeman shifted electronic transition, and recording the fluorescence radiation emitted perpendicular to the excitation laser. This technique has important advantages because the dye laser is the frequency selective element and the magnetic field measurement is reduced to an intensity measurement with the spatial resolution determined by the irradiated volume viewed by the collection optics. The studies were carried out in a high current discharge operated in neon and neon/nitrogen mixtures at pressures of 0.1 to 2 kPa. A grazing incidence flash lamp pumped dye laser having a band width of 0.004 to 0.009-nm was used to fluoresce the 585.25-nm transition in neutral neon. The frequency spectrum of the radiation was recorded with a photomultiplier by scanning the laser frequency. The measurements reveal an LIF spectrum which is double-humped under certain conditions. The overall width of the spectrum is consistent with the Stark broadened line width anticipated for the plasma condition, and the minimum at the line center cannot be attributed to self absorption in the plasma.

Descriptors :   *LASER INDUCED FLUORESCENCE, *ELECTRON BEAMS, ZEEMAN EFFECT, STARK EFFECT, OPTICAL PUMPING, RELATIVITY THEORY, FARADAY EFFECT, SIGNAL TO NOISE RATIO, MAGNETIC FIELDS, FOCUSING

Subject Categories : Particle Accelerators
      Lasers and Masers
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE