[en] A 5 kV electron gun was designed and developed using planar configuration for the focusing electrode and anode. The gun uses a LaB₆ pellet as cathode, which is indirectly heated using a tungsten filament. The gun was used as injector in the 3 MeV DC electron accelerator at EBC, Kharghar. A Titanium window puncture resulted in the cathode poisoning and reduction in beam current. This paper describes the higher power filament heating of the cathode to restore the cathode emission performance, its consequent filament failure, modifications in the gun, and beam characterization on test bench. (author)

[en] Fast Current Transformers are used in RF Linacs to measure beam current and it is an expensive import item. Passive, in-flange FCTs have been designed and developed in-house to measure pulsed beam currents. A soft ferrite (MnZn) core has been used around an Alumina ceramic break and conflate flanges have been welded at both ends. An outer cover has been provided for return path to the image current. The FCT’s are of two different sizes having ferrite cores of ID: 38 mm (FCT I) and ID: 104 mm (FCT II) with CF35 and CF100 end flanges. The optimized number of secondary turns for FCT I and II are 11 and 8 respectively. The calibration of FCT has been done by passing a known pulsed current of duration ∼4.2 μs through the center of the toroid core. The output voltage was measured across a 50μ resistor connected at the secondary. The measured sensitivity of FCT I and FCT II is 2.0 V/A and 2.6 V/A. The beam current from an Electron Gun has been measured at different extraction voltages using indigenous FCT. The results are found to be in good agreement with imported FCT of Bergoz make. At an extraction voltage of 30 kV, beam current measured by indigenous FCT is 496 mA while that by the imported one is 488 mA. (author)

[en] The X-ray imaging has application in various fields including national security. Nowadays, X-ray imaging is used in Container Inspection System (CIS) for scanning the cargos for detecting unauthorized objects at ports (airports, seaports etc). A Container Inspection System typically consists of an X-ray source, an array of detectors, image processing software and control systems. An electron LINAC (e-LINAC) is generally used as an X-ray source in the CIS. An RF e-LINAC of dual energy (4 MeV and 6 MeV) has been developed by the APPD, BARC at the Electron Beam Centre (EBC), Kharghar for the Indian Cargo Scanner (ICS). In this work, measurements of bremsstrahlung spectra for 4 MeV, 6 MeV and dual energy (4 MeV + 6 MeV) electron beam from the e-LINAC at EBC Kharghar is presented. The energy of the electron beam has been estimated from the end point energy of the measured bremsstrahlung spectrum. The detector was energy calibrated using 0.511 MeV and 1.275 MeV photons from ²²Na radioisotope before, during and after the experiment; and the energy calibration was found to be stable during the entire period of the experiment. The experimental data for electron beam energy of 4 MeV, 6 MeV, and the dual mode (4 MeV + 6 MeV) were taken for duration of around three hours each. The background spectrum (i.e. without beam - e-LINAC OFF) was also taken for the same duration