Jayanta Mondal

Characterization and analysis of a pulse power system based on Marx generator and Blumlein.

A pulse power system (1 MV, 50 kA, and 100 ns) based on Marx generator and Blumlein pulse forming line has been studied for characterization of a general system. Total erected Marx inductance and series resistance are calculated from modular testing of Marx generator and testing of Marx generator with Blumlein. The complete pulse power system has been tested with the termination of a liquid resistor load for finding the Blumlein characteristic impedance. Equivalent electrical circuits during the charging and discharging of the Blumlein are constructed from the characterized parameters of the system. These equivalent circuits can be used in the analysis of prepulse voltage and droop in the flat top of the main pulse in the pulse power systems based on Marx generator and Blumlein.

Generation and dose distribution measurement of flash x-ray in KALI-5000 system

Summary form only given. The high intensity pulsed electron beam of KALI-5000 system is used to develop a flash X-ray source. The KALI-5000 system is capable of generating intense relativistic electron beam (IREB) of 1MeV, 60 kA and 100 ns when connected to impedance matched electron beam diode. This system is operated in 6 GW, 100 ns duration to produce the Bremsstrahlung flash X-ray on a tantalum target of planner anode-cathode geometry. The axial and the radial dose distribution are characterized using CaSO4: Dy TLDs (thermoluminescent dosimeter) as well as using the optical densitometer to measure the dose distribution of the exposed X-ray film. The measured dose distribution by TLDs and the optical densitometer plus X-ray film matches within plusmn5%.

RF properties of 1050 MHz, β = 0.49 Elliptical cavity for High Current Proton Acceleration

BARC is developing technology for the accelerator driven subcritical system (ADSS) that will be mainly utilized for the transmutation of nuclear waste and enrichment of U233. Design and development of superconducting medium velocity cavity has been taken up as a part of the accelerator driven subcritical system project. We have studied RF properties of 1050 MHz, β = 0.49 single cell Elliptical cavity for possible use in High Current Proton Accelerator. Cavity shape optimization studies have been done by means of 2D cavity tuning code SUPERFISH and 3D High Frequency Simulation code CST Microwave Studio. The cavity peak electric and magnetic fields, power dissipation Pc, quality factor Q and effective shunt impedante ZT2 were calculated for various cavity dimensions using these codes. Based on these analyses a list of design parameter for the inner cell of the cavity has been suggested for possible use in high current proton accelerator.

Design, fabrication, RF test at 2 K of 1050MHz, β=0.49 single cell large and fine grain niobium cavity

BARC is developing a technology for the accelerator driven subcritical system (ADSS) that will be mainly utilized for the transmutation of nuclear waste and enrichment of U233. Design and prototyping of a superconducting medium velocity cavity has been taken up as a part of the ADSS project. The cavity design for β = 0.49, f = 1050 MHz has been optimized to minimize the peak electric and magnetic fields, with a goal of 5 MV/m of accelerating gradient at a Q > 5 × 109 at 2 K. After the design optimization, two single cell cavities were fabricated from polycrystalline (RRR > 200) and large grain (RRR > 96) Niobium material. The cavities have been tested at 2 K in a vertical cryostat at Jefferson Lab and both achieved the performance specifications.

Gigawatt power generation on KALI system using relativistic backward wave oscillator

Relativistic backward wave oscillators (RBWO) are widely used high power microwave (HPM) devices due to their ease of operation and simple geometry. This paper presents the RBWO power generation experiments carried out on KALI 30 GW pulse power system. We have used 600 kV, 7 kA electron beam to generate 0.8 GW HPM power with 3.28 GHz frequency. A magnetic field coil is designed for retaining this electron beam into its path. The output mode was TM01 mode. It was confirmed by putting a neon lamp array in the far field radiation area of the RBWO antenna.

Sub-nanosecond pulse generator and electron beam source for nToF application

This paper describes a repetitive pulsed power source capable of giving 50-100 kV, 2 ns, 10 Hz pulsed output with sub-nanosecond rise time. The main sub-systems of this pulse generator are air core based, epoxy insulated, pulse transformer, high pressure gas filled pulse forming line (PFL), fast spark gap switch and inductively isolated trigger generator. This system is coupled with an explosive field emission cathode. The generated beam pulses are collected by a suitably designed faraday cup with a proper impedance matching. The measured electron beam pulses are in the range of 30-100 A, 2 ns, 10 Hz. The comparative study has been done for the graphite cathode and carbon fiber cathode in this setup in repetitive operation. This source will be integrated with 1 MeV buncher cavity followed by 30 MeV LINAC for neutron time of Flight studies. Therefore consistency of electron beam generation is critical in nanosecond time domain as well as diagnostic of diode voltage and beam current also.

Beam dynamics studies and parametric characterization of a standing wave electron linac

This paper presents the results of electron beam tracking simulations for a 30 MeV standing wave electron linac at Electron Beam Centre Kharghar, Navi Mumbai, India. For the pulsed mode operation of the present linac preferential operation parameters have been determined from the results of beam dynamics studies. This electron accelerator is a general purpose facility for generation of Bremsstrahlung X-rays and neutron scattering experiments. This electron accelerator-based experimental neutron facility will be used for measurement of neutron cross-section (n,γ), (n, xn) and (n, f) reactions at different energies for various materials and material irradiation studies.

Generation and Dose Distribution Measurement of Flash X-Ray in KALI-5000 System

The high intensity pulsed electron beam of KALI-5000 system is used to develop a flash x-ray source. The KALI-5000 system is capable of generating intense relativistic electron beam (IREB) of 1 MeV, 60 kA and 100 ns when connected to impedance matched electron beam diode. This system is operated in 6 GW, 100 ns duration to produce the bremsstrahlung flash x-ray on a tantalum target of planner anode-cathode geometry. The axial and the radial dose distribution are characterized using CaSO4: Dy TLDs (thermoluminescent dosimeter) as well as using the optical densitometer to measure the dose distribution of the exposed x-ray film. The measured dose distribution by TLDs and the optical densitometer plus x-ray film matches within ± 5%.

Intense Relativistic Electron Beam Diode in Presence of Prepulse

Intense Relativistic Electron beam diode has been operated without a Prepulse switch. A bipolar Prepulse of peak 60 kV voltage has been recorded at the diode voltage. Prepulse generated plasma expands and lowers the impedance of the diode. For small gap Prepulse generated plasma completely fills the anode cathode gap and the diode behaves as plasma filled diode. It has been observed that electron beam can be generated without encountering the closure problem if the Anode Cathode gap is kept larger than that estimated by the Child Langmuir relation. At a large gap the beam parameters obtained are 420 KeV, 22 kA, 100 ns. Intense Electron Beam Diode behavior was studied for various anode cathode gaps and voltages in presence of Prepulse. From the experimentally obtained values of perveance an upper limit was set up for the Marx Voltage (or Anode Cathode Voltage) and lower limit for the Anode Cathode gap in order to avoid the gap closure problem and the diode can be operated with a better shot to shot reproducibility.