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New generation of semiconductor closing switches based on reverse switched dynistors (RSD) has been developed to switch high -power current pulses with microsecond duration. In this report the results of theoretical and experimental investigations of RSD at peak current more than 500 kA and pulse duration up to 500 [ts (at 0.1 Imax) are observed. The criteria of extreme peak current for switch taking into consideration the longtime performance under pulse-periodical mode are gave. The design and test results for switch under single pulse mode at operating voltage up to 25 kV and peak current up to 300 kA are described. The possibility of using such a switch in the ISKRA-6 capacitor bank is estimated.

PACS. 95.80Q -Gamma-ray and elementary particle.PACS. 97.605 -Neutron stars.PACS. 98.70R -Gamma-ray sources. PACS. 97.60Gpulsars.Abstract. -Accumulated y-ray evidence on the time variability of the pulse height ratio (PHR) of the Crab pulsar is shown to be compatible with a long-term (-10.7 y) periodicity and can be interpreted as the free precession of the underlying neutron star. A prediction for the value of PHR by the coming GRO-EGRET y-ray observations under the present model is presented.

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Foreign trade today is one of the most important areas of economic activity in Russia, which is associated with the large strategic role of foreign trade in ensuring the stability of the economy. At the same time, special attention is paid to the development of export trade with a decrease in import volumes. The global crisis against the backdrop of the coronavirus pandemic, of course, had a negative impact on the development of Russia's foreign trade, leading to its decline due to the temporary curtailment of production and economic activities within the country and the closure of national borders between countries in order to prevent the spread of infection. The study examines trends in the development of Russia's foreign trade in the context of the coronavirus pandemic based on an analysis of the dynamics of the main indicators of the country's foreign trade activity in 2020 in comparison with 2019 in the context of quarters and months. It was found that in 2020, coupled with the crisis amid the coronavirus pandemic, Russia's foreign trade activity decreased significantly, which was especially evident by the 2nd quarter of 2020. If by the end of 2019, the country's foreign trade turnover reached $ 184.1 billion, then by the 2nd quarter of 2020 it decreased to $ 124.4 billion. Moreover, the decrease is mainly due to a decrease in the volume of exports, while the volume of imports decreased slightly during the period of active spread of coronavirus. As a result, if in 2019 the volume of the country's exports did not exceed $ 100 billion, then by the 2nd quarter of 2020 it decreased to $ 70.4 billion. Evaluation of the data by months revealed that the largest decline in the value of both exports, and imports, fell on April-August 2020.