1) I.Yu. Senichenkov, E.G. Kaveeva, A.V. Gogoleva, E.O. Vekshina, G.V. Zadvitskiy, P.A. Molchanov, V.A. Rozhansky, S.P. Voskoboynikov, N.A. Khromov, S.A. Lepikhov, V.K. Gusev and The Globus-M Team // Integrated modelling of the Globus-M tokamak plasma and a comparison with SOL width scaling // Nucl. Fusion 55 (2015) 053012 (7pp)

DOI:10.1088/0029-5515/55/5/053012 (http://dx.doi.org/10.1088/0029-5515/55/5/053012)


Recently a scheme for the coupling of the one-dimensional core transport code ASTRA and the two-dimensional edge transport code B2SOLPSwas developed, thus providing the integrated modelling of tokamak discharge. Here, this scheme is improved by taking impurities into account and by considering a real flux surface shape using the equilibrium code SPIDER. This integrated modelling is applied to discharges of the spherical tokamak Globus-M to study the dependence of the scrape-off layer (SOL) width and divertor heat loads on the discharge power and the plasma current. Since these values, together with the magnetic field, are relatively small in Globus-M, this study can test the existing scaling against data in a wider range of tokamak operational parameters. The modelling results agree reasonably with Thomson scattering and Langmuir probe measurements and allow, in principle, the determination of the physical mechanisms responsible for the SOL structure formation. It is found that the SOL width is approximately inversely proportional to the plasma current, in agreement with existing experimental scaling, while its dependence on discharge power is found to be quite weak.

Keywords: transport codes, integrated modelling, plasma edge, SOL width




2) П.Б. Щеголев, Н.Н. Бахарев, В.К. Гусев, Г.С. Курскиев, В.Б. Минаев, М.И. Патров, Ю.В. Петров, Н.В. Сахаров // Первые эксперименты по генерации токов увлечения с помощью атомарного пучка в сферическом токамаке Глобус-М // Журнал технической физики, 2015, том 85, вып. 9

DOI: 10.1134/S1063784215090194 (http://dx.doi.org/10.1134/S1063784215090194)


Представлены результаты исследований токов увлечения в сферическом токамаке Глобус-М, генерируемых путем инжекции пучков атомов водорода и дейтерия. Эксперименты проводились в водородной и дейтериевой плазме токамака, имеющей диверторную конфигурацию с нижней X-точкой, смещение по большому радиусу от −1 до −2.5 cm, тороидальное поле 0.4 T, при токе плазмы 0.17−0.23MA. Пучок инжектировался в токамак в экваториальной плоскости, тангенциально к магнитной оси плазменного шнура, с прицельным параметром 32 cm. В экспериментах использовался источник ионов ИПМ-2 для получения пучка атомов с энергией  28 keV, мощностью до 0.5MW и геометрическими размерами 4×20 cm (по уровню мощности 1/е). Генерация безындукционных токов фиксировалась по одновременному подъему тока и провалу напряжения на обходе. При инжекции водородного и дейтериевого пучков в дейтериевую плазму получен заметный и воспроизводимый провал напряжения на обходе (до 0.5V). С помощью транспортного кода ASTRA построена модель, позволяющая рассчитывать величины безындукционных токов, и проведены расчеты для конкретного разряда, которые подтвердили, что модель удовлетворительно описывает эффект генерации токов увлечения.




3) V.V. Dyachenko, O.N. Shcherbinin, E.Z. Gusakov, V.K. Gusev, M.A. Irzak, G.S. Kurskiev, Yu.V. Petrov, A.N. Saveliev, N.V. Sakharov, S.A. Khitrov, N.A. Khromov, V.I. Varfolomeev and A.V. Voronin // The first lower hybrid current drive experiments in the spherical tokamak Globus-M // Nucl. Fusion 55 (2015) 113001 (7pp)

DOI:10.1088/0029-5515/55/11/113001 (http://dx.doi.org/10.1088/0029-5515/55/11/113001)


First experiments on non-inductive current drive (CD) in the spherical tokamak using lower hybrid (LH) waves at 2.45 GHz are described. The basic characteristics of the new experimental approach utilizing poloidal LH wave slowing-down scheme obtained by modeling are presented at the beginning of the paper. The experimental results for a poloidal slowing-down scheme are described. The CD efficiency comparable or even higher than theoretically predicted is demonstrated in the experiment using a 10 waveguide grill with 120° phase shift between neighboring waveguides.

Keywords: RF current drive, tokamaks, spherical tokamak, grill phasing


4) A.A .Lebedev, B.Ya. Ber, N.V. Seredova, D.Yu. Kazantsev1 and V.V. Kozlovski // Radiation-stimulated photoluminescence in electron irradiated 4H-SiC // J. Phys. D: Appl. Phys. 48 (2015) 485106 (5pp)

doi:10.1088/0022-3727/48/48/485106 (http://dx.doi.org/10.1088/0022-3727/48/48/485106)


The photoluminescence (PL) arising in low doped CVD grown n- and p-type 4H-SiC upon electron irradiation (0,9 MeV) has been studied. After each doze of irradiation spectrum of PL was measured. The PL spectrum was dominated by a band peaked at hv ≈ 2,45 eV, commonly observed upon irradiation of SiC. The experiments demonstrated that, for samples with both types of conduction, the PL intensity approaches a constant value with increasing irradiation dose. A model was suggested, describing the PL characteristics in terms of the radiative recombination via a donor-acceptor pair constituted by nitrogen and a structural defect formed in the course of irradiation. Also, the concentration of nitrogen atoms was measured by the SIMS method. The experimental data were used to calculate in terms of the suggested model the dependence of the PL intensity on the irradiation dose. A good agreement between the calculated and experimental dependences was observed. A conclusion is made that the PL is activated by donor—acceptor pairs constituted by a nitrogen atom and a structural defect.

Keywords: 4H SiC, electron irradiation, photoluminescence, SIMS



5) L.B. Karlina, A.S. Vlasov, B.Y. Ber, D.Y. Kazantsev // Diffusion of zincin gallium arsenide with the participation isovalent impurities // Journal of Crystal Growth 432 (2015) 133–138

DOI: 10.1016/j.jcrysgro.2015.09.015 (http://dx.doi.org/DOI:10.1016/j.jcrysgro.2015.09.015)


The diffusion of Zn into GaAs in the presence of indium and phosphorus was studied. Zn diffusion was performed from the gas phase in a hydrogen flow under isothermal conditions (670 °C). A GaAs substrate was annealed in In and P vapors in a separate chamber. The annealing conditions simulated the memory effect of a MOVPE reactor and/or the cross-doping during the growth of multilayer structures based on III-V alloys. The aim of the current research was to study the effects of In and P on the Zn diffusion processes in GaAs. The results obtained by secondary-ion mass spectrometry show that, upon a pre-treatment with In and P, both the incorporation efficiency and the diffusion rate of Zn increase. Measurements by Raman spectroscopy confirm the increase in the free-hole concentration in the sub-surface layers in pre-annealed samples. The influence of In and P on the diffusion process was observed at concentrations higher than 1017 cm-3. Optical characterization reveals changes in the defect distribution in the GaAs samples. The changes of the recombination processes, caused by In and P, depend on the indium vs. phosphorus ratio. The effective Zn diffusion rate is controlled by this ratio. ©2015 Published by Elsevier B.V.



6) Yu.V. Petrov, N.N. Bakharev, V.K. Gusev, V.B. Minaev, V.A. Kornev, G.S. Kurskiev, M.I. Patrov, N.V. Sakharov, S.Yu. Tolstyakov and P.B. Shchegolev // Effect of toroidal Alfvén eigenmodes on fast particle confinement in the spherical tokamak Globus-M // J. Plasma Phys. (2015), vol. 81, 515810601

DOI:10.1017/S0022377815001129 (http://dx.doi.org/doi:10.1017/S0022377815001129)


In experiments with neutral beam injection at the early stage of a Globus-M discharge, instabilities were observed that were excited by fast ions in the frequency range of 50–200 kHz, which were identified as toroidal Alfvén eigenmodes (TAE) (Petrov et al., Plasma Phys. Rep., vol. 37, 2011, pp. 1001–1005). In contradiction with the NSTX and MAST tokamaks, a regime of TAE generation was realized with strongly developed single modes. Magnetic measurements with fast Mirnov probes have shown that most of the modes have toroidal number $n=1$. The influence of the modes on the fast particle confinement was recorded by means of a tangentially directed neutral particle analyser (NPA) and neutron detector. Hydrogen and deuterium were used as target plasma and injected beam for study of the isotopic effect. At deuterium injection into the deuterium plasma, TAE led to the neutron rate dropping by 25 %, whereas NPA fluxes of high energy dropped by 75 %. At hydrogen injection, the drop in the measured NPA fluxes did not exceed 25 %.



7) V.K. Gusev, N.N. Bakharev, B.Ya. Ber, V.V. Bulanin, F.V. Chernyshev, V.V. Dyachenko, P.R. Goncharov, E.Z. Gusakov, A.D. Iblyaminova, M.A. Irzak, E.G. Kaveeva, S.A. Khitrov, N.A. Khromov, V.A. Kornev, G.S. Kurskiev, A.D. Melnik, V.B. Minaev, A.B. Mineev, M.I. Mironov., A.N. Novokhatsky, M.I. Patrov, A.V. Petrov, Yu.V. Petrov, V.A. Rozhansky, N.V. Sakharov, A.N. Saveliev, I.Yu. Senichenkov, P.B. Shchegolev, O.N. Shcherbinin, S.Yu. Tolstyakov, V.I. Varfolomeev, A.V. Voronin and A.Yu. Yashin // Globus-M plasma physics research for fusion application and compact neutron source development // Plasma Phys. Control. Fusion 58 (2015) 014032 (6pp)

DOI:0.1088/0741-3335/58/1/014032 (http://dx.doi.org/0.1088/0741-3335/58/1/014032)


During the past decade, plasma physics research promoting the physics base of ITER and developing novel concepts such as a compact fusion neutron source has been conducted on the Globus-M spherical tokamak (ST) (R  =  36 cm, a  =  24 cm, I p  ≤  250 kA, B T  ≤  0.4 T). Tokamak reconstruction is imminent. The upgraded tokamak Globus-M2 will have the same vacuum chamber and an enhanced magnetic system to provide B T  =  1 T and I p  =  500 kA. In this paper we outline the most important research directions and the main results obtained on Globus-M and make some predictions about the possibilities and parameters of Globus-M2.



8) Yashin, A.Y., Bulanin, V.V., Petrov, A.V., Petrov, M.A., Gusev, V.K., Khromov, N.A., Kurskiev, G.S., Patrov, M.I., Petrov, Y.V., Tolstyakov, S.Y., Prisyazhnyuk, D.V. // Multi-diagnostic approach to geodesic acoustic mode study // Journal of Instrumentation Volume 10, Issue 10, 15 October 2015, Article number P10023

DOI:10.1088/1748-0221/10/10/P10023 (http://dx.doi.org/10.1088/1748-0221/10/10/P10023)


Multi-diagnostic approach developed for the GAM research in the spherical tokamak Globus M is described. Doppler backscattering (DBS) method as the tool for the GAM study, together with the diagnostics of plasma density and magnetic field GAM oscillations, were simultaneously used in experiments. The version of the DBS diagnostics with two cut-offs positioned at different poloidal angles of the minor cross-section was employed in Globus-M. For the GAM plasma density oscillation study, the Dα emission was observed at different angles to restore the spatial mode structure of the GAM plasma density oscillations. At the same time, the array of Mirnov coils was used for the GAM-like magnetic oscillation study, and that made it possible to restore the magnetic field perturbation spatial structure. The coherent and cross-bicoherence analyzes were employed to identify the interaction between the GAM velocity oscillation and plasma turbulent fluctuations. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics.



9) Е.В. Астрова, А.М. Румянцев, Г.В. Ли, Д.Ю. Казанцев, Б.Я. Бер, В.В. Жданов // Электрохимическое литирование кремния с разной кристаллографической ориентацией // Физика и техника полупроводников, 2016, том 50, вып. 7


Для изучения анизотропии внедрения лития в кремниевые аноды литий-ионных аккумуляторов использовались микроструктуры в виде сетки с вертикальными стенками толщиной 0.5 мкм и пластины монокристаллического кремния, имеющие разную ориентацию. Электрохимическое литирование проводилось при комнатной температуре в гальваностатическом режиме. Исследовались зарядные кривые микроструктурных и плоских кремниевых анодов. С помощью вторичной ионной масс-спектрометрии определялось распределение внедренных атомов Li по глубине пластины. Для анализа экспериментальных данных использовалась двухфазная модель, согласно которой процесс литирования лимитируется скоростью продвижения фронта между аморфным сплавом с высоким содержанием Li и кристаллической кремниевой подложкой. Определено соотношение между скоростями внедрения лития в разные кристаллографические плоскости: (110), (111) и (100) V110 : V111 : V100 = 3.1 : 1.1 : 1.0. Продемонстрировано, что микроструктурные аноды со стенками (110) имеют наиболее высокий циклический ресурс и при скорости заряда/разряда 0.36 С выдерживают ~ 600 циклов.



10) Н.В. Кузнецова, Д.В. Нечаев, Н.М. Шмидт, С.Ю. Карпов, Н.В. Ржеуцкий, В.Е. Земляков, В.Х. Кайбышев, Д.Ю. Казанцев, С.И. Трошков, В.И. Егоркин, Б.Я. Бер, Е.В. Луценко, С.В. Иванов, В.Н. Жмерик // Cолнечно-слепые AlxGa1−xN (x > 0.45) p−i−n-фотодиоды с поляризационно-легированным p-эмиттером // Письма в ЖТФ, 2016, том 42, вып. 12


Исследовано поляризационное p-легирование слоев AlGaN с высоким содержанием Al во время их роста плазменно-активированной молекулярно-пучковой эпитаксией. Продемонстрирована необходимость задания градиента молярной доли AlN в AlGaN на уровне 0.005 nm−1 (градиент состава) для достижения дырочной концентрации на уровне ~ 1018 cm−3 (измеренной C−V-методом) в слоях AlxGa1−xN : Mg (x = 0.52−0.32) c концентрацией примеси [Mg] = 1.3 · 1018 cm−3. Применение таких слоев в качестве p-эмиттеров в p−i−n-фотодиодах на основе гетероструктур AlGaN позволило получить максимальные значения фоточувствительности в солнечно-слепом диапазоне (l = 281 nm) 35 (48)mA/W при обратных смещениях U = 0 (−5)V и плотность темнового тока 3.9 · 10−8 A/cm2 при −5V.