Abstract. A method for determining the conditions of maximum efficiency of a helium vapor flow cryostat designed to maintain a predetermined temperature level of the lens of a cryogenic optoelectronic de-vice is proposed. A mathematical model of the process of cryostatting object cooling with the use of a pipeline mounted on the surface of the object for a constant mass rate flow of helium vapors, is pre-sented. The pipeline contact with the object surface is assumed to be ideal. It is shown that it is neces-sary to ensure full recovery of helium vapors with the pipeline for the most efficient cooling with a mini-mum flow rate of cryoagent. Requirements for the length of the pipeline providing full recovery in the heat exchanger are determined using preliminary calculated thermal efficiency per unit length of the pipeline. This specific index of thermal efficiency (SITE) of the flow heat exchanger is an objective crite-rion of the condition of full recovery. Analytical formulas for calculating the thermal efficiency index for laminar, transient, and turbulent regimes of helium vapor flow are derived. The formulas represent the dependences on the mass flow rate and the diameter of the pipeline accounting for the cryostatting temperature level. The efficiency and convenience of the obtained analytical dependences for practical calculations, as well as for the choice of parameters of flow cryostats are demonstrated.

Keywords: flow cryostat, cryogenic optoelectronic device, helium vapor cooling, cryostat temperature, recovery

References:

1. Miroshnikov M.M. Teoreticheskiye osnovy optiko-elektronnykh priborov (Theoretical Foundations of Optoelectronic Devices), Leningrad, 1977, 600 р. (in Russ.)
2. Khankov S.I. Teoreticheskiye osnovy teplovogo proyektirovaniya teplonagruzhennykh uzlov optiko-elektronnykh sistem (Theoretical Foundations of Thermal Design of Heat-Loaded Nodes of Optoe-lectronic Systems), St. Petersburg, 2002, 182 р. (in Russ.)
3. Oleynikov L.Sh. Krioopticheskiye sistemy (Cryooptic Systems), St. Petersburg, 2013, 352 р. (in Russ.)
4. Khankov S.I. Journal of International Academy of Refrigeration, 2014, no. 1, pp. 46–50. (in Russ.)
5. Khankov S.I. Voprosy Radioelektroniki. Seriya: Tekhnika Televideniya, 2015, no. 3, pp. 136–147. (in Russ.)
6. Baeva Yu.V., Khankov S.I. Voprosy Radioelektroniki. Seriya: Tekhnika Televideniya, 2014, no. 2, pp. 111–125 (in Russ.)
7. Goryankin G.S., Denisov R.N., Ermakov B.S., Markin V.A., Oleynikov L.Sh., Ostanin V.I. Journal of Optical Technology, 1994, no. 1, pp. 71–75.
8. Vinokurov D.K., Kukina G.V., Mishin G.S., Pronin Yu.S. Cosmonautics and Rocket Engineering, 2006, no. 3(44), pp. 137–143.
9. Boytsev A.V., Oleynikov L.Sh., Sergeyev A.O., Sigalov A.V., Khankov S.I. Journal of Instrument Engi-neering, 1986, no. 12(29), pp. 78–81. (in Russ.)
10. Romanenko V.A., Tikhonov S.V., Yagupova N.K., Khankov S.I. Journal of Engineering Physics, 1989, no. 4(56), pp. 617–625. (in Russ.)
11. Galchuk A.B., Lavrenchuk S.V., Romanenko V.A., Khankov S.I. Journal of Engineering Physics, 1989, no. 5(56), pp. 760–767. (in Russ.)
12. Okunev A.V., Oleynikov L.Sh., Romanenko V.A., Tikhonov S.V., Khankov S.I. Journal of Instrument Engineering, 1989, no. 7(32), pp. 76–82. (in Russ.)
13. Klubkov A.G., Romanenko V.A., Khankov S.I. Journal of Engineering Physics, 1990, no. 6(59), pp. 1027–1028. (in Russ.)
14.  Romanenko V.A., Khankov S.I. Journal of Engineering Physics and Thermophysics, 1994, no. 1-2(67), pp. 180–181. (in Russ.)
15.  Dzitoyev A.M., Khankov S.I. Journal of International Academy of Refrigeration, 2014, no. 1, pp. 11–15. (in Russ.)
16.  Formozov B.N. Vvedeniye v kriogennuyu mikroelektroniku (Introduction to Cryogenic Microelectron-ics), St. Petersburg, 2001, 327 р. (in Russ.)
17.  Zolotovskaya S.V., Molchanov A.S. Geliyevyye kriostaty dlya nauchnykh issledovaniy. Osnovy kon-struirovaniya (Helium Cryostats for Scientific Research. Design Basics), Moscow, 1991, 120 р. (in Russ.)
18. Verkin B.I., ed., Metody polucheniya i izmereniya nizkikh i sverkhnizkikh temperatur (Methods of Ob-taining and Measuring Low and Ultra-Low Temperatures), Kyiv, 1987, 232 р. (in Russ.)
19. Verkin B.I., ed., Kriogennaya tekhnika (Cryogenic Technique), Kyiv, 1985, 184 р. (in Russ.)
20. Zeyen C.M.E., Chagnon R., Disdier F., Morin H. Rev. Phys. Appl. (Paris), 1984, no. 19, pp. 789–791.
21. Babenko V.A. Journal of Engineering Physics and Thermophysics, 1992, no. 6(63), December, pp. 1176–1182.
22. Eroshenko V.M., Lubanovskii V.I., Yaskin L.A. Journal of Engineering Physics and Thermophysics, 1983, no. 3(44), March, pp. 250–255.
23. Dul'nev G.N., Semyashkin E.N. Teploobmen v radioelektronnykh apparatakh (Heat Transfer in Elec-tronic Devices), Leningrad, 1968, 360 р. (in Russ.)
24. Malkov M.P., Danilov I.B., Zel'dovich A.G., Fradkov A.B. Spravochnik po fiziko-tekhnicheskim osno-vam kriogeniki (Handbook of the Physical and Technical Foundations of Cryogenics), Moscow, 1985, 432 р. (in Russ.)
25. Akulov L.A., Borzenko E.I., Novotel'nov V.N., Zaytsev A.V. Teplofozicheskiye svoystva krioproduktov (Thermophysical Properties of Cryogenic Products), St. Petersburg, 2001, 243 р. (in Russ.)