Using single particle orbit computations the time-averaged distribution funciton of the electrons accelerated by a localized electric field in a plasma is calculated. This model is applied to the resonant absorption of an electromagnetic wave obliquely incident on a steep plasma density gradient. The calculated distribution function of the electrons accelerated parallel to the density gradient agrees with the results of an electrostatic simulation computer code.
Ideal, gridded, planar electrostatic retarding field analyzers correctly measure isotropic velocity distributions in field-free plasmas if the grid and collector are infinite. However, the finite apertures in practical analyzers block some particles that have sufficient momentum to be collected. We calculated the resulting error in the measured distribution function for a range of analyzer sizes when a Maxwellian distribution enters the analyzer.
The hot-electron plasma produced in a single-stage magnetic mirror compression experiment using a deuterated titanium washer stack source is compared with the nonneutral hot-electron plasma produced using a thermionic electron gun source. Both plasmas contain approximately 5 × 1011 electrons with 0.3-MeV mean energy and 0.3-MeV temperature at the peak magnetic field of 18.5 kG, and both remain trapped for more than 20 msec. These plasmas are similar because deuterated titanium washer stack sources are electron sources during the first few μsec of operation and because the electron dynamics during compression is not strongly affected by the ion dynamics. The effect of the plasma self fields upon synchrotron radiation is investigated. The properties of these plasmas are compared with three other pulse compression hot electron plasmas obtained using a washer stack source.
The distribution function measured using an ideal planar retarding-field energy analyzer external to a finite-size uniform source of particles depends on the location of the analyzer. The error that occurs when this distribution function is used to infer the temperature inside the source is investigated for a variety of source shapes, locations, and potentials when the distribution is both Maxwellian and anisotropic.
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