The high sensitivity of traditional diagnostic methods hinders their application in inertial confinement fusion with the pulsed radiation power of target plasma being as high as 1013–1014 W. Different methods of attenuating the incident radiation flux either alter its characteristics or are too complicated. The results of tests of a new detector, where quartz glass is used as a sensing element, at the Angara-5-1 facility are presented. It is demonstrated experimentally that the detector sensitivity is ~2 V/(MW cm 2 ) and the time resolution is ~1 ns. The mechanism of formation of the response signal, where the temperature of electrons produced under irradiation plays a significant part, is discussed.

ДИЭЛЕКТРИЧЕСКИЙ ДЕТЕКТОР ИНТЕНСИВНЫХ ПОТОКОВ РЕНТГЕНОВСКОГО ИЗЛУЧЕНИЯИ.А

An X-ray detector with a dielectric (KU1 optical glass) used as a sensitive element is described. Operation of the detector is based on the discovered effect of electric-field generation in a dielectric under exposure to radiation. The measurements were taken at the Angara-5-1 facility, at which the radiation source is megaampere Z-pinch plasma. It is shown that when the radiation power incident on the detector is approximately 1 MW/cm2, the detector response is a few volts with a time resolution of 1–2 ns. This effect is thought to be caused by “hot” electrons induced by radiation in the dielectric. The estimates for these experimental conditions are presented.

Исследуется эффект, наблюдающийся при взаимодействии электромагнитного излучения (энергия квантов 25-1000 eV) с диэлектриком, имеющим металлическое покрытие. Источником излучения служил мегаамперный Z-пинч. Измерения, проведенные с образцами оптического стекла, показали, что под действием излучения (мощность ~106 W/сm2) в электрической цепи, включающей металлизированный диэлектрик, возникает ток. Авторы считают, что причиной данного гальванического эффекта является генерация в диэлектрике горячих" электронов.

The effect observed upon interaction between the electromagnetic radiation with quantum energy of 25–1000 eV and a dielectric with metal coating is investigated. The radiation source was a megampere Z-pinch. Measurements performed on optical glass samples showed that radiation with a power of ~106 W/cm2 in the electric circuit switching on the metalized dielectric induces the current. It is shown that the observed galvanic effect originates from the generation of hot electrons in the dielectric.

A radiation foil bolometer intended for measuring radiation-energy fluxes and plasma flows in high-power pulsed plasma X-ray sources is studied. In the bolometer, the radiation or ion-flow energy is absorbed by a 13-μm-thick niobium foil preliminarily heated to T ≈ 1900 K by a quasi-constant current lasting 2 s. Radiation from the foil was fed through an 8-m-long light guide to a semiconductor photodetector. The sensitivity of the instrument obtained from the results of calibrations is 0.56 J/V cm2. The time resolution of this technique (∼2.5 μs) is determined by the foil heating time. In experiments with megaampere Z-pinches, the time resolution attained allows detection of the radiation energy independently of the energy of expanding plasma flows. In this case, the photoelectric effect from X-rays and the conductivity of expanding plasma do not affect the operation of the radiation bolometer. The working capacity of the bolometer was demonstrated at the Angara-5-1 facility in experiments with high-current Z-pinches with a radiation output energy of 50–100 kJ/pulse. The measurements performed have shown that the energy flux density of plasma expanding in the direction perpendicular to the pinch axis is at most 5% of the energy flux density of soft X-rays.