An attempt is made, to obtain mathematical relations correlating the volume and surface effects of the dielectric to those of the electrical impedance of the dielectric system exhibited in the presence of a quasistatic sinusoidal electrical field. A new experiment is described to differentiate clearly the two types of polarizations in an electret.

Microtron electron accelerators generally show a 50% reduction of the injected beam in the first orbits. A modification of the race-track magnet system is proposed in this paper to reduce the beam losses. Calculations of the phases of electrons at the microwave cavity yield exact shapes of different orbits required for resonance in a split magnet system. Introduction of small sector magnets in the field-free space provides a feasible method for obtaining the calculated orbit shapes.

Absorption of polarization in fluorocarbon foil electrets has been studied under different conditions. The mode of surface charge decay of thermo-and radio-electrets has been explained by the mechanism of polarization trapping in electrets.

A modified electron bombardment type ion source suitable for use with mass spectrometer is described. Ion formation occurs throughout a relatively large volume in the ionisation box, since no magnetic field is used to collimate the ionising electrons. A sensitivity of 2 × 10⁻⁵ amp/torr is obtained for an ion extraction energy of 2 keV and 200 mass resolution. Trajectory tracing has been used to study the operation of the ion source. Capability of the ion source to analyse solid samples in microgram quantity was tested by studying evaporation of BaO from tungsten.

Thermally stimulated current spectra of nitrogen implanted fluorinated ethylene propylene polymer foils have been studied. Two characteristic peaks have been obtained for samples implanted with nitrogen ions with energies ranging from 20 to 60 keV. The variations in the activation energies and relaxation times of charge carriers, as a function of implantation energy, have been attributed to the corresponding changes in the carrier distribution in the polymer. The carrier mobilities and mobility life-time products have also been estimated for the two characteristic peaks.

Resistance changes in thin films of copper, aluminium and bismuth have been studied under the bombardment of nitrogen, carbon and argon ions. Variations in resistance with implantation dose have been observed upto doses of ∼ 3 × 10¹⁷ ions/cm² for ion energies in the range 40 to 120 keV. The results are discussed in terms of desorption of gases from the film and a composite action of sputter removal of the film and its structural changes upon ion bombardment. A simple theoretical model is discussed which can qualitatively explain the experimental observations.

This paper describes the operational details of the single-cavity race track microtron of this laboratory. The machine is capable of providing electrons of 8 MeV energy at 1 mA peak current. Important parameters of the machine and beam handling system are studied and the results are reported.

A modified version of vacuum vibrator ion source is designed, fabricated and used to obtain phosphorous and boron ions. Its main features (i) controlled amplitude of vibrations at the spark position and (ii) small quantity requirements of materials. Pure powders of boron and red phosphorous were used respectively to get boron and phosphorous ions and in each case the ion current obtained was of the order of 1µA. The results obtained from silver electrodes are compared with those obtained from other metal electrodes. Silver is found to be a suitable electrode material for production of phosphorous and boron ions.