Abstract: A plasma mass spectrometer has a plasma ion source (1). The source has associated with it an electromagnetic excitation means (2), which may be one or more induction coils. The excitation means is powered by an RF generator (3). Ions are sampled from the plasma ion source through an interface (15) into a vacuum chamber (16). The stream of ions is directed by an ion optics element (4) through a mass analyser (5) to an ion detector (6). The excitation means may include means (7) for altering the axial component of the electromagnetic field sustaining the plasma. Alternatively or additionally, the spectrometer may include signal detecting means (11,17) to provide feedback enabling optimisation of parameters.

Abstract: A method of isolating selected ion species in a quadrupole ion trap mass spectrometer is disclosed. One or more ranges of masses to be eliminated from the ion trap are ejected by applying a supplemental dipole excitation waveform, sparsely populated with frequency components, while the trapping field is modulated. The spacing of the frequency components in the supplemental excitation waveform varies across the range of frequencies in the waveform. Preferably, the frequency range is divided into a plurality of subranges, and the spacing of the frequency components in each of the subranges is constant. A method of creating a master set of frequencies used for generating a supplemental excitation waveform is also shown. Likewise, a method of calculating edge frequencies defining a gap in the mass spectrum that is excited by the supplemental waveform is also shown.

Abstract: An ultra high vacuum (UHV) joint is scaled by an elastomer O-ring (7) between adjacent flanges (3,4), fitting in a seal cavity formed by grooves (41,42) in the flange (3,4) surfaces. The groove surfaces (41,42) are highly polished and shaped such that the O-ring (7) conforms to the groove surfaces (41,42) and contacts them substantially entirely when the flanges (3,4) are clamped together. This improved structure significantly reduces the permeation through and the gas leakage around the seal (7). The resulting seal (7) can support a vacuum of 10.sup.-11 torr or better. The conformal-groove geometry of the present invention can be used with seals other than elastomer seals, such as soft metal seals (55,65).

Abstract: An optical pulse propogating in an optical guide of an electro-optic medium interacts with a coplanar RF traveling wave to shift the optical wavelength. The RF phase is resynchronized to the optical pulse phase with spatial periodicity to provide a desired phase relationship between RF and optical radiation. A unidirectional incremental wavelength shifter comprises a frequency multiplexer for soliton communication and a symmetrical sideband modulator of this type varies the spectral width of probe illumination in an atomic absorption spectrometer probe beam.