Energy Dependence of the Sensitivity of an Ion Energy and Mass Spectrometer
| Authors | |
|---|---|
| Year of publication | 2006 |
| Type | Article in Periodical |
| Magazine / Source | Czechoslovak Journal of Physics B |
| MU Faculty or unit | |
| Citation | |
| Field | Plasma physics |
| Keywords | plasma; IED; IAD; mass spectrometry; plasma process monitor |
| Description | The aim of this work was to estimate the energy dependence of the transmission function of an ion energy and mass spectrometer (Plasma Process Monitor PPM 421, Balzers). Firstly, the energy dependence of the critical angle for ions impinging on an orifice in the extraction hood was calculated. The critical angle is defined as the largest angle between the ion velocity and the optical axis of the entry ion optics enabling the ion to go through the entry optics into the energy analyzer. For the calculation the programs ELD and TRASYS were used. The transmission of the entry ion optics was evaluated by integrating the ion angle distribution (IAD) up to the critical angle. Since the IADs are usually not known, an approximate method for the IAD estimation was suggested. The method suppose that the ion velocity component perpendicular to the optical axis has Maxwell distribution and the longitudinal velocity component is increased in the sheath. It is suitable for low-pressure discharges, where the requirement of little effect of the collisions on the IAD is satisfied. It was shown that in comparison with the case of isotropic IAD, the spectrometer transmission does not have critical influence on the measured ion energy distribution. |
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