Absorbed power of the neutral-injection beam in spherical tokamaks Globus-M/M2 is estimated numerically. Deceleration of fast particles is simulated by means of the NUBEAM code. The signal of analyzer of charge-exchange atoms is simulated by means of the FIDASIM code using the distribution function of fast ions calculated by means of the NUBEAM code. Comparison of calculated and experimental signals allowed determining the degree of influence of instabilities on confinement of fast particles along with absorbed beam power.

Исследован нагрев плазмы одним и двумя инжекторами быстрых нейтральных атомов в сферическом токамаке Глобус-М2 при тороидальном магнитном поле 0.8–0.9 Тл и токе плазмы 0.35–0.4 МА. Измерение пространственных распределений температуры и концентрации электронов, выполненные диагностикой томсоновского рассеяния лазерного излучения, показало двукратный нагрев электронов плазмы при инжекции нейтральных частиц с энергией до 45 кэВ при мощности пучка 0.75 МВт по сравнению с омическим режимом. Дополнительное включение второго пучка с энергией частиц до 30 кэВ и мощностью до 0.5 МВт позволило получить режим с горячими ионами в диапазоне значений средней плотности плазмы 1.6–10 × 10 19 м –3 . По данным активной спектроскопии и корпускулярной диагностики температура ионов достигла величины 4 кэВ при плотности плазмы 8 × 10 19 м –3 в горячей зоне, превысив температуру электронов более чем в 2.5 раза.

The paper discusses the results of the calibration of two corona neutron counters used to measure the total neutron yield from the plasma of the Globus-M2 tokamak. The calibration was carried out in the experimental hall of the Globus-M2 facility using an AmBe source. During the calibration, the source moved uniformly around the central solenoid in the equatorial plane of the vacuum chamber, and one of the detectors was gradually moved away from the tokamak along a line with a constant toroidal angle. The values of the calibration coefficient obtained depending on the distance of the detector from the tokamak axis are presented. The calibration technique made it possible to separate in the detector signal the contributions from the direct neutron flux emitted by the plasma and from the flux of neutrons scattered on the elements of the experimental hall.

Full-particle modeling of gamma-ray and proton induced extensive air showers (EASs) in the Earth's atmosphere as well as Monte Carlo modeling of photon transport in a small size Cherenkov telescope and signal registration with its camera based on the OnSemi MicroFJ SiPM detectors have been performed. Calculations have been carried out for primaries within the 0.3 - 30 TeV range and a telescope with a 10 m(2) mirror similar to the unit employed at the TAIGA observatory. It has been shown that even with strict selection criteria aimed at high quality EAS images, the threshold detection energy of the SiPM-based camera would not exceed 0.8 TeV - about twice as low as the current threshold of the TAIGA-IACT camera based on vacuum photomultipliers.

The results of the measurements of the neutron and gamma radiation produced in the 9 Be( 3 He,pγ) 11 B and 9 Be( 3 He,nγ) 11 C nuclear reaction at the 2.57 MeV energy of the 3 He ions are represented. The measurements were carried out with organic scintillation detector BC-501A and semiconductor HPGe spectrometers. Gamma-ray spectra were measured at 0°, 30°, 60°, 90° and 120° angles. The shapes of the gamma lines 6.9 MeV from the 9 Be( 3 He,nγ) 11 C reaction and 8.92 MeV from the 9 Be( 3 He,nγ) 11 C were obtained. The angular distribution of protons populating the 8.92 MeV energy level of the 11 B nucleus was reconstructed. The energy distribution of the neutrons produced in the 9 Be( 3 He,nγ) 11 C reaction was measured (obtained).

With an increase of magnetic field up to 0.8 T and plasma current to 400 kA, fast ion losses rate in the discharges with toroidal Alfven eigenmodes decreased in tokamak Globus-M2 comparing with Globus-M tokamak discharges. Taking into account the data on the discharges with increased magnetic field and plasma current, the regression fit of neutral particle analyzer flux drop in energy channel close to neutral beam energy on relative eigenmode magnitude, the value of magnetic field and plasma current was analyzed. The power of flux drop dependence on TAE magnitude was found to be ~0.5 and inverse proportional on the value of product of magnetic field and plasma current, which is highly likely is determined only by plasma current due to weak dependence on magnetic field. The result obtained indicates that fast ion losses in Globus-M2, stimulated by toroidal Alfven eigenmodes are mostly determined by the shift of passing orbits to the plasma edge. With the increase of plasma current and magnetic field, neutron flux drops arising in the moments of toroidal mode bursts have also decreased.

We have modeled propagation of source signal and noise for a future camera of TAIGA-IACT Cherenkov gamma-ray telescope, which will be based on silicon photomultipliers sensitive in the 240 -- 600 nm range. It has been shown that employment of such detectors instead of traditional vacuum photomultipliers will allow one to decrease the energy threshold by a factor of about 2.5: from ~ 1.5 TeV down to ~ 0.6 TeV. We have also shown that application of a standard ultraviolet filter ZWB3 will decrease the source signal by a factor of 3, while the noise signal from the night sky will be decreased by a factor of 6. In this way the duty cycle of the telescope can be extended (the telescope will be able to operate during moonlit nights and during twilight) and the energy threshold further decreased down to ~ 0.3 TeV. A narrow 260 -- 300 nm filter can be employed to improve gamma-hadron separation of primary cosmic particles in the ~ 25 -- 50 TeV band.

Source and noise signals in a new camera of the TAIGA-IACT Cherenkov γ-ray telescope based on silicon photomultipliers (SiPM) have been simulated. It is shown that application of modern silicon photomultipliers as detecting elements of TAIGA-IACT (instead of the currently used conventional vacuum photomultipliers) will make it possible to reduce the threshold detection energy of cosmic γ quanta by a factor of about 2.5 (from ≃1.5 to ≃0.6 TeV). It is also shown that employment of a standard ZWB3 UV filter mask in the TAIGA-IACT camera would reduce the average signal level by a factor of about 3 and the noise (background) level from the night sky by a factor of about 6, which would allow one to extend the duty cycle of the telescope (in particular, to carry out observations during moonlit nights and twilights) and to additionally reduce the threshold detection energy down to ≃0.3 TeV. The application of a narrower UV filter of 260–300 nm bandwidth can increase the efficiency of determining the primary particle type (γ-hadron separation) in the energy range from ~25 up to ~50 TeV.

Studying the mechanism of Alfvén wave generation in plasma is important, since the interaction of these waves with energetic particles in tokamak-type reactors can increase the losses of energy and particles with the corresponding decrease in the efficiency of plasma heating and, under certain conditions, lead to the damage of structural elements of the system. Despite the previous detailed investigations of the excitation of Alfvén waves by superthermal particles in regimes with additional heating, the physics of Alfvén mode generation in discharges with ohmic heating of plasma is still not sufficiently studied. We have established that a significant factor inf luencing the development of Alfvén oscillations in ohmic discharge is the presence of runaway electrons. A physical mechanism explaining this relationship is proposed.

Исследование механизмов генерации альфвеновских волн в плазме является важным, поскольку взаимодействие этих волн с энергичными частицами в токамаке-реакторе может привести к увеличению потерь энергии и рабочего вещества и соответствующему снижению эффективности нагрева плазмы, а при определенных обстоятельствах --- к разрушению конструктивных элементов установки. Несмотря на то, что вопросы возбуждения альфвеновских волн надтепловыми частицами в режимах с дополнительным нагревом изучались подробно, физика механизмов возбуждения этих волн в разрядах с омическим нагревом плазмы остается недостаточно исследованной. Показано, что существенным фактором, влияющим на развитие альфвеновских колебаний в омических разрядах, является наличие убегающих электронов. Предложен физический механизм, объясняющий обнаруженную взаимосвязь.

Приведены основные характеристики прибора ПИНГВИН-М, запущенного на орбиту в составе космического аппарата КОРОНАС-ФОТОН 30 января 2009 г. Прибор состоит из блока детекторов ПИНГВИН-МД (ПМД) и блока электроники ПИНГВИН-МЭ (ПМЭ). Цель эксперимента – измерение степени линейной поляризации рентгеновского излучения солнечных вспышек в энергетическом диапазоне 20–150 кэВ и энергетических спектров рентгеновского излучения солнечных вспышек в диапазоне энергий 2–500 кэВ. В статье дается описание прибора, процедуры калибровки, полетной настройки и краткое описание первых результатов измерений.

A setup is developed for measuring the spectra of wideband semiconductors (III nitrides) and related heterostructures. The setup makes it possible to trace the time distribution of the luminescence intensity at a fixed wavelength with a resolution of ±5 ns and a sampling rate of up to 10 MHz in the time interval from several microseconds to several hundreds of microseconds. Also, it plots the integral intensity of luminescence versus the wavelength. Precision measurement conditions are provided.

A multichannel multistop time analyzer that provides the measurement of the time intervals between start and stop pulses and the accumulation of their time distribution in the memory of its unit is described. The time of arrival of a stop signal is recorded at a resolution of ±5 ns and a dead time of 30 ns. The number of stops per start can achieve 6000. The number of channels is 131072 (217). The time analyzer is based on a CAMAC unit and can be used to design measurement-information systems for solving problems in neutron spectrometry and mass spectrometry by time-of-flight methods and for studying the time characteristics of luminescence radiation.