Electrodynamic multichannel ion spectrometer for the individual analysis of individual ion pulses

摘要

Conventional detection systems for the analysis of ion pulses from local, short-lived plasmas use electromagnetic constant (DC) fields. These require a successive measurement method. In contrast, electrodynamic multichannel ion spectrometers having a deflection field alpha 1/t<2> permit the analysis of individual ion pulses. Internal space charge expansions of the ion beams hitherto limit the resolution power (resolving power) very markedly. In the novel multi-channel ion spectrometer (16) the space charge expansion is to be reduced. For this purpose, a construction is chosen for the selector (17) which has the effect of focusing the angle to at least the first order. Collectors (9) for receiving the separated ion currents are arranged, at least approximately, in the focal plane. The correct curve of the deflection field is ensured for example by applying suitable voltages to correcting metal sheets (6). In a preferred construction the deflection voltage is present between two plane-parallel, conductive plates (1, 2). The ion current enters and leaves through diaphragm or discharge openings (4, 5) in the earthed bottom plate (1). Equations for choosing the deflection voltage and determining the focal plane are specified. Particle analysis in methods which are based on local, short-lived plasmas, for example in situ process controls in thin-film methods on the basis of laser-produced plasmas. <IMAGE>