A microwave detector based on an MCT photodiode for subthermonuclear plasma research |
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Authors: | V V Vasilyev S A Dvoretsky V S Varavin N N Mikhailov I V Marchishin Yu G Sidorov A O Suslyakov V N Ovsyuk V S Burmasov S S Popov E P Kruglyakov A L Aseev |
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Affiliation: | (1) Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia;(2) Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia |
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Abstract: | A microwave detector including a single-element infrared (IR) photodiode mounted in a cooled Dewar and a preamplifier is developed. An IR photodiode of the n +-p type is created on the basis of mercury-cadmium telluride (HgCdTe or MCT) heteroepitaxial structures grown by means of molecular beam epitaxy. A special profile of MCT structures throughout the MCT layer thickness ensures a low series resistance of less than 10 Ω and a high quantum efficiency at a level of 0.65 without any antireflection coating. For the spectral range of 8 to 12 μm, IR photodiodes are characterized by a low threshold power of 3.8·10?13 W·Hz?1/2 and 10?19 W·Hz?1 in the direct and heterodyne regimes, respectively. The cooled Dewar maintains the operating temperature of the IR photodiode in the interval of 77 to 80 K for 8. The preamplifier operates in a frequency range up to 1 GHz. With the use of this microwave detector, a method is developed for detection of intensity of a CO2 laser beam on plasma fluctuations caused by heating by a relativistic electron beam (REB). At high REB intensities, dips of the turbulence signal with a duration of several nanoseconds are observed, which is interpreted as a collapse of Langmuir waves. |
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