Features

The instrument’s primary purpose is to investigate the identity and energy of ions that might strike the mirror surface in a plasma generated by the client’s equipment. The identity is assessed by measuring the mass to charge ratio, using mostly pre-existing Kore designs for an orthogonal injection, time-of-flight mass spectrometer (TOFMS). The advantage of TOFMS, in this context, is that it is able to measure a wide range of masses simultaneously with good sensitivity. The energy of ions is measured by arranging things in such a way that, at a given setting, only a relatively narrow range of ion energies at the entrance will yield a signal. The settings can then also be adjusted to vary the ion energy that is transmitted, over the range of energies of interest, to yield an energy profile.

A secondary experiment is to be able to assess the neutral gas composition in the plasma chamber. For this purpose, a simple small electron impact ion source is also included.

Features:

• Parallel detection of all ion masses.
• Energy analysis by inexpensive computer controlled filtering.
• Mass resolution of m/Δm ≈ 1000 FWHM at 4 Daltons.
• Includes ioniser for neutral species.
• Custom designed magnetic shielding of transfer optics with minimal disturbance to the plasma field.
• Compact, 4 inch tube based spectrometer.
• Built on adjustable frame for offering up to client equipment.
• Supplied with simple ion source for commissioning and calibration check.

The energy scan shown above was taken when using the simple surface ionisation source supplied for commissioning purposes. The full-width-half-maximum resolution is about 1.8eV, which is achieved at low cost and without compromise to the sensitivity. For users requiring more resolution, tighter apertures could be fitted, at the expense of sensitivity.