GB1158241A - Mass Spectrograph. - Google Patents

Abstract

1,158,241. Mass spectrometers. NIHON DENSHI K.K. 5 Feb., 1968 [3 Feb., 1967], No. 5762/68. Heading H1D. In a mass spectrometer employing an r<SP>-1</SP> dispersing magnetic sector field between two focusing sector fields at least one of which is a homogeneous magnetic field, the ion path through the two magnetic fields has the same radius of curvature and a single excitation coil is provided for generating both magnetic fields. As described the spectrometer utilizes a 112À15 degrees toroidal electric focusing field followed by a 200À32 degrees r<SP>-1</SP> magnetic dispersing field and a 13À59 degrees homogeneous magnetic focusing field, the radius of the beam path in all fields being 30 cm. The magnet comprises a central core 19 surrounded by an excitation coil and has upper and lower yoke plates 18, 26 with upper and lower conical polepieces 24a, 24b on either side of the analyser tube 22. At one end of the conical polepieces are parallel-faced polepieces 27a, 27b for providing the homogeneous field. Knock pins 12a in cylindrical supports 13a are provided around the periphery of the magnet to allow for adjustment of the magnetic gaps. At other points around the periphery provision is made for inserting or withdrawing wedge-shaped members between upper and lower collars attached to the polepieces to make the adjustment. The adjustment is then set by means of bolts pressing on to the upper polepiece. A Herzog shunt for reducing stray magnetic fields is arranged at each end of the structure.