Study of Mode Converter for 42 GHz, 200 KW Gyrotron

Singh, BP and Alaria, MK and Sinha, AK (2012) Study of Mode Converter for 42 GHz, 200 KW Gyrotron. In: National Conference on Recent Trends in Microwave Techniques and Applications (Microwave - 2012), July 30 - August 1, 2012, S.S. Jain Subodh P.G. College, Jaipur and University of Rajasthan . (Submitted)

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Abstract

Gyrotron is a high power microwave tube, which emits coherent radiation at approximately the electron cyclotron frequency or its harmonics. Gyrotron is widely used in Plasma fusions, ECRH heating, Industrial heating and Material processing. The need for high power, high frequency rf sources for the magnetic fusion research experiments has provided much of the impetus for the development of present day gyro oscillators. A mode converter for a microwave system, said mode converter being able to receive microwave energy at an input thereof in the form of a input mode (like TM01 mode) of circular waveguide, said mode converter being able to fundamental required mode (like TE01 mode). Based on the mode coupling theory, circular waveguide mode converter for Gyrotron is discusses in detail. The mode converter is used to transform the TE03 operating mode to the TE01 mode for injection into a corrugated transmission line. The design of the mode converter is very crucial to ensure high conversion efficiency and also prevent reflection of the power back in to the tube. An external mode converter necessary for this gyrotron is likely to be large and demands a lot of care in the assembly and mounting of the mode converter. The design is described below. The mode converter system includes three sections: (1) Rippled-wall TE03-to-TE01 mode converter, (2) Bent waveguide TE01-to-TM11 mode converter, (3) Tapered corrugated waveguide TM11-to-HE11 mode converter. An approximate design of these components is given here; however, a more rigorous analysis should be used for the final design. Coupled mode analytical theory can be used to design the rippled-wall mode converter. The number of periods of sinusoidal ripples should be larger than 3 to apply the analytical theory. We used 5 periods in this preliminary design. The period length is the bounce wavelength between the modes TE03 and TE01 in an 85 mm diameter waveguide.

Item Type:	Conference or Workshop Item (Paper)
Subjects:	?? TK ?? Microwave Tubes > Gyrotrons
Divisions:	Microwave Tubes
Depositing User:	Mr. Jitendra Nath Bajpai
Date Deposited:	23 May 2013 09:35
Last Modified:	23 May 2013 09:35
URI:	http://ceeri.csircentral.net/id/eprint/39

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