NOVEL DESIGN OF A SPHERICAL ELECTRON SPECTROMETER

The design procedure of a 'simulated' spherical electron spectrometer is described. This device has spherical equipotentials in the region of the beam trajectories, whereas its electrodes are non-spherical. The electron optical properties of the new device are very close to those of a spherical spectrometer. Its geometric width, however, is only about one-third that of a conventional hemispherical spectrometer. Because of its simple electrode structure, gridded or corrugated electrodes can be used easily to suppress background electrons. A prototype of the new instrument was employed as an electron monochromator. An energy spread of less than 25 meV was achieved.