Electrostatic Energy Analyzer (ESA)

Plasma Controls' electrostatic analyzer (ESA) is used to obtain ion and electron energy distribution functions (EDF). Our ESA features spherical segments and a narrow ion acceptance angle. Unlike a retarding potential analyzer (RPA), ESA traces do not need to be differentiated to obtain IEDFs/EEDFs. An ESA selects ions with equal charge-to-mass ratios. Our ESA can be combined with our ExB probe to provide energy-specific charge state data. Plasma Controls can provide custom cables, feed-thrus, and measurement equipment to meet specific needs.

Dimensions: 10.8 D x 18.3 W x 5.0 T cm

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Theory of Operation

Electrons or ions enter a small aperture, and are deflected by an electric field to a current detector. The amount of deflection is proportional to the particle's energy. More correctly, in electrostatic devices, charged particles are measured according to energy-to-charge ratio rather than absolute velocity. In fact, particles of equal energy-to-charge state ratio (E/q) but different mass-to-charge state ratio (m/q) cannot be distinguished using only electrostatic deflection. The measured current is typically in the nano- or even pico-amp range; an electron multiplier can be added to the detector to measure very low signals.

Typical Data

The figure at right shows ion energy distributions measured downstream of an ion source, where the ion source's beam energy was set to several different values.