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Asian Journal of Physics Vol 32, Nos 9 – 12 (2023) 639-647

Design, development and qualification of permanent magnet based
focusing lens for X-band relativistic backward wave oscillator

Mahima, Janvin Itteera, Kumud Singh, Sanjay Malhotra, R R Singh, and Rajesh B Chimurkar
Electromagnetic Applications & Instrumentation Division
Bhabha Atomic Research Centre- 400 088, Mumbai, India
Dedicated to Prof B N Basu

The need for a compact and reliable focusing lens for X-band relativistic backward wave oscillator ( RBWO) inspired the use of permanent magnets. With the advent of rare earth materials, it has become possible to develop compact focusing lens using permanent magnets. Permanent magnets provide an attractive viable option with better portability and greater reliability to the RF oscillator. Beam optics require an axial magnetic field density of 0.73 T with non-homogeneity less than ± 2.5% to be generated in a 176 mm long interaction region. A detailed electromagnetic analysis with TOSCA has been performed to optimize design parameters of the focusing lens and the magnetic flux density has been estimated over the interaction region. The fabrication and assembly intricacies towards the development of the magnetic lens are also briefly discussed in this paper. Magnetic field profile of the developed magnet is found to match the design estimates and a uniformity of 95% is achieved in the interaction region with average magnetic field density 0.73T. © Anita Publications. All rights reserved.
Keywords: Relativistic Backward Wave Oscillator, Confinement, Focusing, Permanent Magnet.

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Method: Single- anonymous; Screened for Plagiarism? Yes
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