The University of Michigan
Department of Aerospace Engineering
| Plasmadynamics & Electric Propulsion Laboratory |
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Plasma Diagnostics

Parallel-Plate Energy Analyzer

An electrostatic diagnostic that determines ion energy distribution and examines ion energy properties.


Figure 1. Schematic of the parallel-plate energy analyzer.

Figure 2. Photograph of PEPL's parallel-plate energy analyzer with cover removed (from ref. 2).

A parallel-plate type electrostatic energy analyzer consists of two parallel plates separated by a distance d. One of the plates is electrically grounded while the other is biased to a positive potential, Vr. Ions enter through a sampling orifice and transit through a drift tube before entering the section composed of the two charged plates. The electrostatic field between these plates causes the ion trajectories to curve in a parabola. At the output of the analyzer is a slit that leads to a detector. Due to the geometry of the system, only ions with a specific energy-to-charge ratio will reach the detector. By varying the field between the charged plates, the entire spectrum of ion energies can be measured. However, while a doubly charged ion will be accelerated to twice the kinetic energy of a singly charged ion, they will have the same energy-to-charge ratio. In order to examine the difference between these states, it is necessary to use a second instrument, a Time of Flight Mass Spectrometer (TOF).

 

Selected Relevant Publications

  1. Beal, B. E., "Clustering of Hall Effect Thrusters for High-Power Electric Propulsion Applications," Ph.D. Dissertation, University of Michigan, 2004.
  2. Walker, M. L. R., "Effects of Facility Backpressure on the Performance and Plume of a Hall Thruster," Ph.D. Dissertation, University of Michigan, 2005.
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