High-Speed Monitoring of Dust Particles in ITER ELMs Simulation Experiments with QSPA Kh-50

Dust generation under powerful plasma stream impacts has been studied in ITER ELM simulation experiments with QSPA Kh-50 plasma accelerator. Repetitive plasma exposures of tungsten have been performed by 0.25 ms plasma pulses and the heat load varied in the range (0.1÷1.1) MJm-2. Main characteristics of dust particles such as a number of ejected particles, their velocity, angular distribution and start time from the surface are investigated. Dust particles have not been observed under heat load below the cracking threshold. Quantity of dust particles rises with increasing heat load. Average velocities of dust particles are found to be strongly dependent on their start time from the surface after beginning of plasma-surface interaction. Maximal velocity achieved a few tens of meters per second

Local Magnetohydrodynamic Characteristics of the Plasma Stream generated by MPC

This paper investigates the spatial distributions of electrical current which flows inside the plasma stream generated by a magnetoplasma compressor (MPC). Two different modes of MPC operation with different gas supply scenarios have been applied in the experiments presented here. The first is the operation mode with a pulse injection of xenon into the interelectrode space, and the second is the operation mode with residual helium in the chamber and local injection of xenon directly into the compression zone. The maximum value of the electric current observed outside the MPC channel is 15 ÷ 20% of the total discharge current. Electric current vortices were discovered in the plasma stream. The amplitude of the current in the vortices reaches 50% of the total discharge current. The maximum EUV radiation power was measured in the mode of MPC operation with local xenon injection. Power in the wave range 12.2 ÷ 15.8 nm achieves up to 16 ÷ 18 kW

Local Magnetohydrodynamic Characteristics of the Plasma Stream generated by MPC

This paper investigates the spatial distributions of electrical current which flows inside the plasma stream generated by a magnetoplasma compressor (MPC). Two different modes of MPC operation with different gas supply scenarios have been applied in the experiments presented here. The first is the operation mode with a pulse injection of xenon into the interelectrode space, and the second is the operation mode with residual helium in the chamber and local injection of xenon directly into the compression zone. The maximum value of the electric current observed outside the MPC channel is 15 ÷ 20% of the total discharge current. Electric current vortices were discovered in the plasma stream. The amplitude of the current in the vortices reaches 50% of the total discharge current. The maximum EUV radiation power was measured in the mode of MPC operation with local xenon injection. Power in the wave range 12.2 ÷ 15.8 nm achieves up to 16 ÷ 18 kW

Characteristics of plasma streams and optimization of operational regimes for magnetoplasma compressor

The main objective of these studies is characterization of dense xenon plasma streams generated by magnetoplasma compressor (MPC) in different operational regimes. Optimization of plasma compression in MPC allows increase of the plasma stream pressure up to 22…25 bar, average temperature of electrons of 10…20 eV and plasma stream velocity varied in the range of (2…9)×10⁶ cm/s depending on operation regime. Spectroscopy measurements demonstrate that in these conditions most of Xe spectral lines are reabsorbed. In the case of known optical thickness, the real value of electron density can be calculated with accounting self-absorption. Estimations of optical thickness were performed and resulting electron density in focus region was evaluated as 10¹⁸ cm⁻³. Remove selectedПроведено експерименти з оптимізації режимів роботи МПК та виміряно параметри плазмових потоків при роботі на ксеноні. Проаналізовано розподіли тиску в плазмовому потоці, швидкість та температура плазми. Спектроскопічні вимірювання показали, що більшість спектральних ліній ксенону самопоглинені. У випадку відомої оптичної товщини, реальна електронна густина може бути обчислена з урахуванням ефекту самопоглинання. Були проведені оцінки оптичної товщини, в результаті чого розрахована величина концентрації електронів в області компресії – 10¹⁸ см⁻³.Проведены эксперименты по оптимизации режимов работы МПК, измерены параметры плазменных потоков при работе на ксеноне. Проанализированы распределения давления в плазменном потоке, скорость и температура плазмы. Спектроскопические измерения показали, что большинство спектральных линий ксенона самопоглощены. В случае известной оптической толщины реальная электронная плотность может быть вычислена с учетом эффекта самопоглощения. Проведены оценки оптической толщины, в результате чего рассчитано значение концентрации электронов в области компрессии – 10¹⁸ см⁻³

On the Semantics of Plates from the Shilovka Burial Ground

Among the finds made on the sites located in the Middle Volga region and Siberia, ivory plaques of high artistic value used to adorn combat saddle pommel are met. They would bear floral ornamentation or depict hunting scenes, reflecting the spiritual world of a nomad warrior. These images are dated widely, but not later than the 7th or 8th centuries. They were drawn with a sharp cutter and blackened down the lines. Of special interest are the bone plates from the Shilovka burial ground site (Uyanovsk oblast) with the following images: two dragons in a heraldic posture, deer hunt scenes, horsemen in ambush, fight with a bear, and defense of the fortress. In the author’s opinion, the Shilovka plates depict a dramatic episode in the life of a Turkic warlord, which occurred in the midst of hostilities. During the hunt, a huge bear was unleashed against him. Part of his heavily armed convoy (or suite) fled; some soldiers got ambushed (the enemy shot them from armor-piercing bows). Saving his life, the captain knelt and bent his bow, whose string broke at the most inopportune moment. Perhaps he died fighting a bear. One can assume that it was a stratagem of the enemy, which decided the outcome of the war. The symbol of victory on the plates is represented by the dragons, frozen in a heraldic posture, and expressing the basic principle of life characteristic of the nomad warriors in the Early Middle Ages: prosperity and well-being at a price of war and victories. The plaques were placed into the winner’s grave