Персона: Кирнева, Наталья Александровна
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Working area of the mephist tokamak: Preliminar estimation ОБЛАСТЬ РАБОЧИХ ПАРАМЕТРОВ ТОКАМАКА МИФИСТ: ПРЕДВАРИТЕЛЬНАЯ ОЦЕНКА
© 2020 National Research Center Kurchatov Institute. All rights reserved.Small spherical tokamak MEPHIST is under construction at the NRNU MEPhI. This paper is devoted to the analysis of the working area of the MEPHIST tokamak and modeling of ohmic discharges in the different plasma configurations, which can be obtained in it.
Physics research on the TCV tokamak facility: from conventional to alternative scenarios and beyond
The research program of the TCV tokamak ranges from conventional to advanced-tokamak scenarios and alternative divertor configurations, to exploratory plasmas driven by theoretical insight, exploiting the device's unique shaping capabilities. Disruption avoidance by real-time locked mode prevention or unlocking with electron-cyclotron resonance heating (ECRH) was thoroughly documented, using magnetic and radiation triggers. Runaway generation with high-Z noble-gas injection and runaway dissipation by subsequent Ne or Ar injection were studied for model validation. The new 1 MW neutral beam injector has expanded the parameter range, now encompassing ELMy H-modes in an ITER-like shape and nearly noninductive II-mode discharges sustained by electron cyclotron and neutral beam current drive. In the H-mode, the pedestal pressure increases modestly with nitrogen seeding while fueling moves the density pedestal outwards, but the plasma stored energy is largely uncorrelated to either seeding or fueling. High fueling at high triangularity is key to accessing the attractive small edge-localized mode (type-II) regime. Turbulence is reduced in the core at negative triangularity, consistent with increased confinement and in accord with global gyrokinetic simulations. The geodesic acoustic mode, possibly coupled with avalanche events, has been linked with particle flow to the wall in diverted plasmas. Detachment, scrape-off layer transport, and turbulence were studied in L- and H-modes in both standard and alternative configurations (snowflake, super-X, and beyond). The detachment process is caused by power `starvation' reducing the ionization source, with volume recombination playing only a minor role. Partial detachment in the H-mode is obtained with impurity seeding and has shown little dependence on flux expansion in standard single-null geometry. In the attached 1,-mode phase, increasing the outer connection length reduces the in-out heat-flow asymmetry. A doublet plasma, featuring an internal X-point, was achieved successfully, and a transport barrier was observed in the mantle just outside the internal separatrix. In the near future variableconfiguration baffles and possibly divertor ptunping will be introduced to investigate the effect of divertor closure on exhaust and performance, and 3.5 MW ECR and 1 MW neutral beam injection heating will be added.
Possibility of using the 140 GHZ frequency for ECR plasma heating in the T-15MD Tokamak ВОЗМОЖНОСТЬ ИСПОЛЬЗОВАНИЯ ЧАСТОТЫ 140 ГГЦ ДЛЯ ЭЦР-НАГРЕВА ПЛАЗМЫ В ТОКАМАКЕ Т-15МД
© 2021 National Research Center Kurchatov Institute. All rights reserved.Electron-cyclotron heating is one of the methods of additional plasma heating in the T-15MD tokamak. The article considers the possibility of plasma heating using an extraordinary wave on the third harmonic of electron-cyclotron resonance at a frequency of 140 GHz. It has been shown that in accordance with the calculations by quasi-linear OGRAY code, a high fraction of single-pass absorption (up to 96%) can be expected even when the ECR is turned on with an ohmic background. Increase of this fraction with the increase in plasma temperature agrees with the theoretical predictions. Vertical power launch seems to be most attractive. Possible engineering solutions for implementation of such a scheme are proposed.
On the Possibility of Applying ECR Heating and Current Drive in the DEMO-S and DEMO-FNS Facilities
Gyrotron setup for ECR-heating system of T-15MD TOKAMAK
© 2020 SPIE. All rights reserved.The paper presents gyrotron-based system (developed by IAP RAS jointly with GYCOM Ltd.) for ECR plasma heating in the new T-15MD tokamak which is under construction in National Research Center "Kurchatov Institute". The first of a series (8 units) of microwave setups of a megawatt power level was developed and successfully tested. The setup includes a gyrotron, set of power supplies, a microwave radiation transmission line, and a fast protection system. 1 MW/82.6 GHz generation regime during 30 second pulse with an efficiency of 57% was experimentally demonstrated.
A Variable Structure Control Scheme Proposal for the Tokamak a Configuration Variable
Fusion power is the most significant prospects in the long-term future of energy in the sense that it composes a potentially clean, cheap, and unlimited power source that would substitute the widespread traditional nonrenewable energies, reducing the geographical dependence on their sources as well as avoiding collateral environmental impacts. Although the nuclear fusion research started in the earlier part of 20th century and the fusion reactors have been developed since the 1950s, the fusion reaction processes achieved have not yet obtained net power, since the generated plasma requires more energy to achieve and remain in necessary particular pressure and temperature conditions than the produced profitable energy. For this purpose, the plasma has to be confined inside a vacuum vessel, as it is the case of the Tokamak reactor, which consists of a device that generates magnetic fields within a toroidal chamber, being one of the most promising solutions nowadays. However, the Tokamak reactors still have several issues such as the presence of plasma instabilities that provokes a decay of the fusion reaction and, consequently, a reduction in the pulse duration. In this sense, since long pulse reactions are the key to produce net power, the use of robust and fast controllers arises as a useful tool to deal with the unpredictability and the small time constant of the plasma behavior. In this context, this article focuses on the application of robust control laws to improve the controllability of the plasma current, a crucial parameter during the plasma heating and confinement processes. In particular, a variable structure control scheme based on sliding surfaces, namely, a sliding mode controller (SMC) is presented and applied to the plasma current control problem. In order to test the validity and goodness of the proposed controller, its behavior is compared to that of the traditional PID schemes applied in these systems, using the RZIp model for the Tokamak a Configuration Variable (TCV) reactor. The obtained results are very promising, leading to consider this controller as a strong candidate to enhance the performance of the PID-based controllers usually employed in this kind of systems.
Possibility of Using the 140 GHz Frequency for ECR Plasma Heating in the T-15MD Tokamak
On the selection of electron-cyclotron heating frequency for T-15md tokamak
© 2020 National Research Center Kurchatov Institute. All rights reserved.Electron cyclotron heating is one of the methods of additional plasma heating and noninductive current drive in T-15MD tokamak. One to eight gyrotrons with a total power up to 7 MW will be used. The frequency of the microwave used depends on the parameters of the experimental scenarios in which the heating will be used and on the physical tasks for which it is intended. This article provides justifica-tion for the choice of the gyrotronsi frequency f1 ° 82.6 GHz for the start-up phase and for the first plasma experiments, and considers the possibility of using this frequency at the stage of full-scale experiments. In order to provide flexibility of the .-15MD ECRH system, it is proposed to consider the possibility of the development of a gyrotron complex based on two-frequency gyrotrons with f1 ~ 82.6 GHz and f2 in the range of ~ 102-X110 GHz.
Current status of tokamak T-15MD
© 2021 Elsevier B.V.At the present time, the preparation to physical start-up of tokamak T-15MD is completed in the National Research Center “Kurchatov Institute”. The main parameters of T-15MD are: R = 1.48 m, a = 0.67 m, B = 2.0 T, Ipl = 2.0 MA. The magnet system is capable to maintain without overheating (more 60 °C) the plasma current of 2 MA for 4 s, 1 MA for 20 s, 700 kA for 40 s, 500 kA for 80 s, 300 kA for 160 s and 250 kA for 400 s. Plasma current drive can be maintained either by injection of fast neutrals or by electron cyclotron (EC)-, ion cyclotron (IC)- and low hybrid (LH) - waves. In August 2019 the electromagnetic system, consisting of TF and PF coils, together with vacuum vessel have been assembled in experimental hall. Power supply system of Tokamak T-15MD includes: two substations 110/10 kV, two substations 10/0.83 kV, thyristor convertors and different equipment. Total power consumption during the pulse with plasma current 2 MA and additional plasma heating of 20 MW will consist of 300 MVA. Power supply system is in the commissioning. Tokamak T-15MD will be operate using the information and control system. All the information and control system equipment, required for the implementation of physical start-up of tokamak T-15MD, is available. For plasma control the 250 different electromagnetic probes are installed inside vacuum vessel. The gyrotron with frequency 82.6 GHz and power of 1 MW will be used for pre-ionization.