• V K Senecha

      Articles written in Pramana – Journal of Physics

    • Optimization studies of photo-neutron production in high-𝑍 metallic targets using high energy electron beam for ADS and transmutation

      V C Petwal V K Senecha K V Subbaiah H C Soni S Kotaiah

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      Monte Carlo calculations have been performed using MCNP code to study the optimization of photo-neutron yield for different electron beam energies impinging on Pb, W and Ta cylindrical targets of varying thickness. It is noticed that photo-neutron yield can be increased for electron beam energies $\geq 100$ MeV for appropriate thickness of the target. It is also noticed that it can be maximized by further increasing the thickness of the target. Further, at higher electron beam energy heat gradient in the target decreases, which facilitates easier heat removal from the target. This can help in developing a photo-neutron source based on electron LINAC by choosing appropriate electron beam energy and target thickness to optimize the neutron flux for ADS, transmutation studies and as high energy neutron source etc. Photo-neutron yield for different targets, optimum target thickness and photo-neutron energy spectrum and heat deposition by electron beam for different incident energy is presented.

    • Dosimetric measurements and Monte Carlo simulation for achieving uniform surface dose in pulsed electron beam irradiation facility

      V C Petwal J N Rao Jishnu Dwivedi V K Senecha K V Subbaiah

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      A prototype pulsed electron beam irradiation facility for radiation processing of food and medical products is being commissioned at our centre in Indore, India. Analysis of surface dose and uniformity for a pulsed beam facility is of crucial importance because it is influenced by various operating parameters such as beam current, pulse repetition rate (PRR), scanning current profile and frequency, scanning width and product conveying speed. A large number of experiments are required to determine the harmonized setting of these operating parameters for achieving uniform dose. Since there is no readily available tool to set these parameters, use of Monte Carlo methods and computational tools can prove to be the most viable and time saving technique to support the assessment of the dose distribution. In the present study, Monte Carlo code, MCNP, is used to simulate the transport of 10 MeV electron beam through various mediums coming into the beam path and generate an equivalent dose profile in a polystyrene phantom for stationary state. These results have been verified with experimentally measured dose profile, showing that results are in good agreement within 4%. The Monte Carlo simulation further has been used to optimize the overlapping between the successive pulses of a scan to achieve $\pm 5%$ dose uniformity along the scanning direction. A mathematical model, which uses the stationary state data, is developed to include the effect of conveyor speed. The algorithm of the model is discussed and the results are compared with the experimentally measured values, which show that the agreement is better than 15%. Finally, harmonized setting for operating parameters of the accelerator are derived to deliver uniform surface dose in the range of 1–13 kGy/pass.

    • Microwave power coupling with electron cyclotron resonance plasma using Langmuir probe

      S K Jain V K Senecha P A Naik P R Hannurkar S C Joshi

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      Electron cyclotron resonance (ECR) plasma was produced at 2.45 GHz using 200 – 750 W microwave power. The plasma was produced from argon gas at a pressure of $2 \times 10^{−4}$ mbar. Three water-cooled solenoid coils were used to satisfy the ECR resonant conditions inside the plasma chamber. The basic parameters of plasma, such as electron density, electron temperature, floating potential, and plasma potential, were evaluated using the current–voltage curve using a Langmuir probe. The effect of microwave power coupling to the plasma was studied by varying the microwave power. It was observed that the optimum coupling to the plasma was obtained for $\sim$ 600 W microwave power with an average electron density of $\sim 6 \times 10^{11}$ cm$^{−3}$ and average electron temperature of $\sim$ 9 eV.

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