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В работе проведён анализ влияния режимов возбуждения термофона на его акустическую эффективность. В настоящее время для возбуждения современных термофонов используют два режима возбуждения соответствующих случаям, когда в активном элементе термофона текут: 1) постоянный электрический ток I0 и переменный электрический ток i(f) = Imsin(ωt); 2) только переменный ток i(f) = Imsin(ωt). В этих случаях термофон излучает звуковые волны, амплитуды колебательных скоростей которых um1 и um2 соответствуют номерам режимов. При этом показано, если выполняется неравенство I0 >> Im, то отношение колебательных скоростей um1 / um2 ≥ 28. Как следствие этого, уровень излучения звука при 1 режиме возбуждения более чем на 29 дБ выше, а мощность акустического излучения в 860 раз выше по сравнению со вторым режимом возбуждения. Таким образом, для создания мобильных эхолокационных систем, работающих в газах, могут быть использованы термофоны, в которых реализован первый режим возбуждения, имеющий более сложную схему электрического питания. The paper analyzes the influence of thermophone excitation modes on its acoustic efficiency. Currently, to excite modern thermophones, two excitation modes are used corresponding to cases when in the active element of the thermophone flows: 1) direct electric current I0 and alternating electric current i(f) = Imsin(ωt); 2) only alternating current i(f) = Imsin(ωt). In these cases, the thermophone emits sound waves whose vibrational speed amplitudes um1 and um2 correspond to the mode numbers. It is shown that if the inequality I0 >> Im, is satisfied, then the ratio of vibrational speeds um1 / um2 ≥ 28. As a result, the sound radiation level at 1 excitation mode is more than 29 dB higher, and the acoustic radiation power is 860 times higher compared to the second excitation mode. Thus, to create mobile echolocation systems operating in gases, thermophones can be used, in which the first excitation mode is implemented, which has a more complex electrical power supply scheme.

This work is of a survey nature based on the results of studies of the processes of sound emission in gases and liquids by thermo-acoustic film sources - thermophones. The purpose of the article is to show the features of the calculation, operation and determination of the main acoustic characteristics of thermophones, ways to increase the efficiency of their radiation and directions of possible practical application.The basic relations and formulas are presented, the calculation of which is confirmed by the experimental results carried out, analyzed ways to excite and improve the effectiveness of thermophones.Film thermophones of various shapes without a thermally insulating substrate have uniform, reproducible acoustic characteristics, which can be predicted by calculation, knowing the thermal-physical constants of the materials used for the construction of thermophones. As the active elements of guns are used for a thin film formed by the vacuum deposition of metals on surfaces of bearing plates made of polymer materials. When passing through the active element of an alternating electric current with a frequency f, an acoustic wave is emitted at a doubled frequency of 2f. Film thermophone are the only sources of sound emitting surface which meets the definition of a piston radiator. Thermopane work in the frequency range from 1.0 to 150 kHz.A promising direction of research is the use of thermophones as sources of radiation of sound in a liquid medium. The results of a study of the radiation of a film thermophone in two liquids (distilled water and kerosene) are presented. Compared to radiation to air, radiation to kerosene, for example, is about 20 dB higher.