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Title: Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas

Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d = 2 mm and varying width, x = 1.0, 1.6, and 2.75 mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.
Authors:
; ; ; ;  [1] ;  [2]
  1. National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)
  2. School of Physics, Trinity College, Dublin 2 (Ireland)
Publication Date:
OSTI Identifier:
22303444
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALUMINIUM; ELECTRON-ION COLLISIONS; ENERGY SPECTRA; ION DENSITY; IONS; LANGMUIR FREQUENCY; LANGMUIR PROBE; LASER-PRODUCED PLASMA; LASERS; OSCILLATIONS; PERIODICITY; PLASMA CONFINEMENT; PLASMA EXPANSION