A mass spectrometer which has a toroidal electrostatic field and a uniform magnetic field with non-zero entrance and exit angles, and which is so constructed that the incident end surface of an ion beam on the toroidal electrostatic field defines a concave surface and that the entrance angle and the exit angle of the ion beam relative to the uniform magnetic field are in the positive direction and the negative direction, respectively, thereby to make the elimination of second-order aberrations and axial focusing possible.

Process and apparatus for varying the deflection of the path of a charged particle beam over a path of length l in a space volume V, where there is a magnetic induction B (x,y,z), wherein a relative displacement of volume V with respect to the beam is produced in such a way as to vary the magnitude .intg.BDl calculated along the path and characterizing the deflection undergone by the beam on passing through volume V. In some of the embodiments rotating magnetic pole pieces are employed to vary the path. Fixed inclined faced pole pieces are also employed.

A portable mass spectrometer is described having one or more electrostatic focusing sectors and a magnetic focusing sector, all of which are positioned inside a vacuum chamber, and all of which may be adjusted via adjustment means accessible from outside the vacuum chamber. Mounting of the magnetic sector entirely within the vacuum chamber permits smaller magnets to be used, thus permitting reductions in both weight and bulk.

A method for achieving optimum selection of machining parameters and tool inserts for finish turning operations is provided. The method allows for the simultaneous consideration of the various machining performance criteria which are highly interactive and need to be taken into consideration when defining optimum cutting conditions or selecting optimum tool inserts. The method broadly includes the steps of (1) developing a process model relating performance variables for said operation with process parameters for said operation; (2) applying multiple criteria optimization techniques to construct a utility function relating the tool life and material removal rate for optimization, using surface roughness, cutting power, and chip breakability as constraints; (3) applying non-linear programming techniques to the process model so that optimum cutting conditions may be selected for given machining performance requirements. This method may also take into account the progressive wear state of the tool being used.