Vol. 68
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2018-04-27
Design and Development of Millimeter Wave Interferometer Circuit for Real-Time Measurement of Plasma Density
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Progress In Electromagnetics Research M, Vol. 68, 1-10, 2018
Abstract
A 3-mm wave interferometer is designed and developed to measure the electron density online at the central chord of Aditya tokamak, unambiguously. The scheme used for this has the advantages in operating the interferometer without a source frequency modulation and easy data processing. The central chord of a 3-mm wave homodyne interferometer system is modified to make a quadrature circuit by using phase shifters and magic tees. This is used to produce the sine/cosine fringe signals. These outputs are amplified and converted into pulses and passed to wired logic up/down fringe counter. Digital synchronous logic circuit is implemented in a Complex Programmable Logic Device (CPLD), followed by digital to analog converter (DAC) and scaler which produces a voltage proportional to increase or decrease in plasma density in real time. The paper presents about this technique and test results of the fringe counter with artificial signals. The chord averaged plasma density ne = 0.9 × 1013 cm-3 is measured online at Aditya tokamak using this interferometer.
Citation
Praveen Kumar Atrey, Dhaval A. Pujara, Subroto Mukherjee, Umesh Nagora, Praveenlal Edappala, Praveena Kumari, and Rachana Rajpal, "Design and Development of Millimeter Wave Interferometer Circuit for Real-Time Measurement of Plasma Density," Progress In Electromagnetics Research M, Vol. 68, 1-10, 2018.
doi:10.2528/PIERM18011502
References

1. Bhat, S. B., D. Bora, B. N. Buch, C. N. Gupta, K. K. Jain, R. Jha, P. I. John, P. K. Kaw, A. Kumar, S. K. Mattoo, C. Natarajan, R. Pal, H. A. Pathak, H. R. Prabhakara, H. D. Pujara, V. N. Rai, C. V. S. Rao, M. V. V. S. Rao, K. Sathyanarayana, Y. C. Saxena, and G. C. Sethia, "ADITYA: The first Indian tokamak," Indian J. Pure Appl. Phys., Vol. 27, 710-742, 1989.

2. Atrey, P. K., S. B. Bhat, D. Bora, B. N. Buch, C. N. Gupta, K. K. Jain, R. Jha, P. I. John, P. K. Kaw, A. Kumar, S. K. Mattoo, C. Natarajan, R. Pal, H. A. Pathak, H. R. Prabhakara, H. D. Pujara, V. N. Rai, C. V. S. Rao, M. V. V. S. Rao, K. Sathyanarayana, Y. C. Saxena, and G. C. Sethia, "Measurement of chord averaged electron density in ADITYA using 100 GHz and 136 GHz interferometers," Indian J. Phys., Vol. 66(B), 487-489, 1992.

3. Heald, M. A. and C. B. Wharton, Plasma Diagnostics with Microwaves, Wiley, New York, 1978.

4. Bora, D. and P. K. Atrey, "Plasma density measurement using a simple microwave technique," Rev. Sci. Inst., Vol. 59, 2149-2151, 1988.
doi:10.1063/1.1139977

5. Franco, S., Design with Operational Amplifiers and Analog Integrated Circuits, McGraw-Hill Education, 2014.