Any axially symmetric electrode system constitutes an electrostatic lens (see Section 4–4). The most distinctive feature of the electrostatic lens is that for nonrelativistic case the focusing properties as well as the aberrations are independent of the charge-to-mass ratio of the particles, therefore if a system is t o be used with different ions, electrostatic lenses must be applied. This is a consequence of the scaling laws of Section 2-8. Since the refractive power of axially symmetric magnetic lenses is roughly proportional to the charge-to-mass ratio [see Eqs. (4-51) and (4-117)], electrostatic lenses are especially suitable for the control of heavy ions.
KeywordsSpherical Aberration Chromatic Aberration Principal Plane Refractive Power Voltage Ratio
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