We consider the coherent properties of short-wavelength radiation generated by high-current nanosecond discharges. The first part of the paper is concerned with the feasibility of using a plasma soft X-ray radiation source, the X-pinch, proposed at the Lebedev Physical Institute in the late 1970s as part of the inertial thermonuclear fusion program based on high-current nanosecond discharges. Experimental studies of the X-pinch suggest that a high-temperature plasma with extreme parameters is produced in it, which emits a high-power electromagnetic pulse in a broad wavelength range, with the X-ray radiation source (1 keV < E < 10 keV) possessing unique parameters. Its dimensions are so small (< 1 μm) that the radiation it emits is spatially coherent. When it was used in projection radiography, phase contrast was observed in images of low-absorbing objects. The results of assessing the applicability of the wave approximation in image analysis and simulations of the intensity distribution in images using Fresnel integrals are presented. In the second part of the paper, we analyze a new physical phenomenon, also discovered at the Lebedev Physical Institute, related to the production of a short (< 2 ns), narrowly directed electromagnetic radiation pulse in the pre-breakdown stage of a high-current discharge on the surface of a ferrite, 50% of the energy spectrum of which lies in the X-ray region (h\ν > 1 keV) with an energy of ~0.6 mJ and average power of ~0.3 MW. The pulse propagates parallel to the ferrite surface towards the anode with a low angular divergence of

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Keywords: X-pinch, high-current nanosecond discharges, soft X-rays, spatial and temporal coherence, phase contrast, low-divergence short electromagnetic pulses, short-term magnetization, ferrites PACS: 52.58.Lq, 52.59.−f, 52.80.Qj (all) DOI: 10.3367/UFNe.2024.02.039642 URL: https://ufn.ru/en/articles/2024/8/f/ Citation: Tilikin I N, Pestovskii N V, Tskhai S N, Shelkovenko T A, Pikuz S A, Savinov S Yu "Coherent properties of high-current nanosecond discharge radiation" Phys. Usp. 67 (8) (2024) Received: 9th, October 2023, revised: 1st, February 2024, accepted: 7th, February 2024 Оригинал: Тиликин И Н, Пестовский Н В, Цхай С Н, Шелковенко Т А, Пикуз С А, Савинов С Ю «Когерентные свойства излучения сильноточных наносекундных разрядов» УФН 194 865–880 (2024); DOI: 10.3367/UFNr.2024.02.039642