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ABSTRACT
A scheme for generating tunable terahertz radiation using relativistic electron beam-induced upper hybrid wave immersed in a magnetized plasma is investigated. The ponderomotive force applied to the beam electrons because of electromagnetic radiation wave and pump wave generates the non-linear current density in the high-frequency regime. For an appropriate pump wave frequency, under the condition of phase matching the THz radiation wave is obtained. The enhancement in the radiation power occurs along the axial direction in the vicinity of Cerenkov resonance. Our analytical expression shows that the growth rate in the unstable modes of the THz radiation wave increases with beam density (beam current) and the modulation index. In addition, the growth rate of the instability decreases with an increase in radiation wave frequency and scales as the inverse cube root of radiation frequency. An interesting result obtained from our model is that an increase in cyclotron frequency causes the growth decrement in THz radiation emission, while the efficiency of THz radiation emission increases with the growth rate and the modulation index. Also, the emission of the THz radiation wave becomes larger as the modulation index approaches unity.
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Notes on contributors
Pratibha Malik
Pratibha Malik received her M. Tech. degree in Engineering Physics from USBAS, Guru Gobind Singh Indraprastha University, Delhi, India, in June 2008. She is currently pursuing her Ph.D. degree in Plasma Physics and working as Teaching Cum Research Fellow with the Department of Applied Physics, Delhi Technological University, Delhi, India. Her current research interest includes Terahertz radiation generation using pre-bunched electron beams and charged particle acceleration.
Suresh C. Sharma
Suresh C. Sharma is currently working as Professor & Head with the Department of Applied Physics, Delhi Technological University (DTU), Delhi, India. He was awarded the Young Scientist project as a principal Investigator by the Department of Science and Technology (DST), Govt. of India for a two-year duration (1997–99) and worked with the Department of Physics and Astrophysics, University of Delhi from 6 January 1997 to 14 October 1997. He was a Monbusho Postdoctoral Fellow under Japanese Govt. fellowship, Dept. of Physics, Faculty of Science, Ehime University, Matsuyama, Japan from October 1997 to March 1999. In addition, he has been a JSPS (Invitation) Postdoctoral Fellow and visiting researcher from May 2004 to October 2005 with the Center for Atomic and Molecular Technologies (CAMT), Osaka University, Japan. Besides, he was awarded Senior Research Associate under the Scientist's Pool Scheme by CSIR, Govt. of India for a 3-year duration (1999–2002) and worked in the Department of Physics and Astrophysics, University of Delhi from April 1999 to January 2002. He has worked on several research projects in India and abroad. He has guided numerous Ph.D., M. Tech and B. Tech students. He has published 138 research papers in journals of international repute and proceedings of international conferences. Prof. Sharma is a Member of the American Physical Society (APS), USA; Member of the Institute of Electrical and Electronics Engineers (IEEE), USA; Member of the International Association of Engineers (IAENG), Hong Kong; Member of the National Academy of Sciences (MNASc), India; Life Member-Plasma Science Society of India (PSSI); Life Member-Indian Science Congress Association (ISCA) and Life Member-Indian Society for Technical Education (ISTE), New Delhi, India. His current research interest includes Plasma Physics/Plasma Applications, Nanotechnology, High Power Microwave Devices, Dusty Plasma/Strongly Coupled Dusty Plasma, THz Radiation Emission/Short Pulse lasers and Plasma Medicines.
Rinku Sharma
Rinku Sharma received her Ph.D. degree in Atomic, Molecular & LASER Physics from Delhi University, Delhi, India, in 1999. Presently, she is working as Professor with the department of Applied Physics, Delhi Technological University, Delhi, India. Her research interests include Collisions in Intense Short Laser Pulses, Atomic structure calculations for multi-electron atoms and ions using Configuration Interaction Technique, Electron impact Excitation Collision Strengths and Rate Coefficients having application in Astrophysics, Plasma Physics and Nuclear Fusion Reactors, Photoionization of complex ions and atoms, Plasma Physics/Plasma Applications, Nanotechnology, THz Radiation Emission and linear & non linear properties of low dimensional structures. Prof. Sharma is a Life Member -Indian Society for Technical Education (ISTE), New Delhi, India; Member, American Physical Society, USA and Advisory Editor of Journal of Atomic, Molecular, Condensate and Nano Physics.