Patent ID: 7777179

Claim:
An ion energy analyzer for use in diagnosing the ion energy distribution (IED) of plasma, comprising: an entrance grid exposed to the bulk plasma volume at a reference voltage and located at an outermost plane of the ion energy analyzer, said entrance grid comprises a plurality of openings, wherein a size of each of said plurality of openings is selected to be sub-Debye length or smaller for said plasma such that a plasma sheath at a boundary of said plasma at said outermost plane remains relatively unperturbed and said plasma sheath does not penetrate said entrance grid and extend into the ion energy analyzer; an electron rejection grid disposed proximate to said entrance grid, wherein said electron rejection grid is coupled to an electron rejection voltage source configured to negatively bias said electron rejection grid at an electron rejection voltage; an ion current collector disposed proximate to said electron rejection grid, wherein said ion current collector is coupled to an ion selection voltage source configured to positively bias said ion current collector at an ion selection voltage; and an ion current meter coupled to said ion current collector and configured to provide a signal related to said selected ion current.