| 1. |
- Eliasson, Bengt, et al.
(author)
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Nonlinear aspects of quantum plasma physics : Nanoplasmonics and nanostructures in dense plasmas
- 2009
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In: Plasma and Fusion Research. - : Japan Society of Plasma Science and Nuclear Fusion Research. - 1880-6821. ; 4, s. 032-
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Journal article (peer-reviewed)abstract
- We present a short review of recent developments in nonlinear quantum plasma physics, including quantum hydrodynamic and effective nonlinear shrödinger equation formalisms, for describing collective phenomena in quantum plasmas. As examples we discuss simulation studies of the formation and dynamics of dark solitons and vortices, and of nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) in dense in quantum electron plasmas. The electron dynamics of dark solitons and vortices is governed by a pair of equations comprising the nonlinear Schrödinger and Poisson equations. Both dark solitons and singly charged electron vortices are robust, and the latter tend to form pairs of oppositely charged vortices. The two-dimensional quantum electron vortex pairs survive during collisions under the change of partners. The dynamics of the CPEM waves is governed by a nonlinear Schrödinger equation, which is nonlinearly coupled with the Schrödinger equation of the EPOs via the relativistic ponderomotive force, the relativistic electron mass increase in the CPEM field, and the electron density fluctuations. The present governing equations in one spatial dimension admit stationary solutions in the form dark envelope solitons. The nonlinear equations admit the modulational instability of an intense CPEM pump wave against EPOs, leading to the formation and trapping of localized CPEM wave envelopes in the electron density holes that are associated with positive potential profiles.
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| 2. |
- Kovtun, Yurii, V, et al.
(author)
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ICRF Plasma Production with Hydrogen Minority Heating in Uragan-2M and Large Helical Device
- 2023
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In: Plasma and Fusion Research. - : Japan Society of Plasma Science and Nuclear Fusion Research. - 1880-6821. ; 18:2402042
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Journal article (peer-reviewed)abstract
- This report compares results ion-cyclotron range of frequencies (ICRF) plasma production at hydrogen mi-nority regime in Uragan-2M (U-2M) and Large Helical Device (LHD). The condition of the presence of the fundamental harmonic ion cyclotron resonance zone for the hydrogen inside the plasma column should be ful-filled for this method. The scenario is successful at both machines and weakly sensitive to the variation of the hydrogen concentration in the H2+He gas mixture. It should be noted that at LHD the start up is slower than at U-2M. The comparison of plasma production in ICRF with hydrogen minority at U-2M and LHD indicate that this scenario can be scaled to larger stellarator devices. The experiments made are the base for the proposal for usage this scenario for plasma production in ICRF at Wendelstein 7-X at magnetic field reduced to 1.7 T.
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| 3. |
- KOVTUN, Yurii V., et al.
(author)
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ICRF Plasma Production with the W7-X Like Antenna in the Uragan-2M Stellarator
- 2022
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In: Plasma and Fusion Research. - : Japan Society of Plasma Science and Nuclear Fusion Research. - 1880-6821. ; 17:0
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Journal article (peer-reviewed)abstract
- The results of the plasma start-up with ICRH of U-2M RF discharges in H2+He mixture with newly implemented controlled gas H2 concentration are presented. The W7-X like ICRH antenna operated in monopole phasing with applied RF power of ∼ 100 kW. We investigated plasma start-up in the pressure range p = 6×10−4 - 9 × 10−2 Pa. Plasma production with an average density of up to Ne ∼ 1013 cm−3 was observed at frequencies the fundamental harmonic of the hydrogen cyclotron frequency.
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| 4. |
- Romanelli, M., et al.
(author)
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JINTRAC: A system of codes for integrated simulation of Tokamak scenarios
- 2014
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In: Plasma and Fusion Research. - : Japan Society of Plasma Science and Nuclear Fusion Research. - 1880-6821. ; 9:SPECIALISSUE.2
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Journal article (peer-reviewed)abstract
- Operation and exploitation of present and future Tokamak reactors require advanced scenario modeling in order to optimize engineering parameters in the design phase as well as physics performance during the exploitation phase. The simulation of Tokamak scenarios involves simultaneous modeling of different regions of the reactor, characterized by different physics and symmetries, in order to predict quantities such as particle and energy confinement, fusion yield, power deposited on wall, wall load from fast particles. JINTRAC is a system of 25 interfaced Tokamak-physics codes for the integrated simulation of all phases of a Tokamak scenario. JINTRAC predictions reflect the physics and assumptions implemented in each module and extensive comparison with experimental data is needed to allow validation of the models and improvement of Tokamak-physics understanding. © 2014 The Japan Society of Plasma Science and Nuclear Fusion Research.
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| 5. |
- Tendler, Michael
(author)
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Issues of Electric Fields in Fusion Devices
- 2010
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In: Plasma and Fusion Research. - 1880-6821. ; 5:S21004
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Journal article (peer-reviewed)abstract
- At present it is well understood that the key element in the transition physics is the origin of the strong radialelectric field and suppression of the turbulence fluctuation level by a strong poloidal rotation in the E × B fields.As a result, the transport coefficients are strongly reduced at fixed places and transport barriers with steep densityand temperature gradients are formed near the separatrix or the last closed flux surface (ETB) or in the core region(ITB). The key element in the transition physics is the origin of the strong radial electric field. The impact of themomentum transport is brought to light.
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| 6. |
- Vicente, Jose, et al.
(author)
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Blobs on the High Field Side of Tokamaks
- 2010
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In: Plasma and Fusion Research. - 1880-6821. ; 5:S2013
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Journal article (peer-reviewed)abstract
- Turbulence-induced high density filaments, blobs, might represent the new paradigm for radial convectivetransport in the Scrape-Off-Layer of magnetic fusion devices. Models for individual blob dynamics, consideringtheir generation on the Low Field Side (LFS) of the torus have been put forward. We investigate the existence ofblobs in the peripheral region of the High Field Side (HFS) of the FT-2 tokamak. Langmuir probe measurementsare used to detect and characterize blobs. The results were obtained in plasmas with enhanced Lower HybridHeating and data was acquired with a new fast data acquisition system with 50MHz sampling rate. While themajority of the blobs are observed to move towards the wall as expected, some are observed to move inwardstowards the core. This effect is not understood in the light of existing models for the LFS where only the outwarddirection is expected. Further characterization of plasma blobs should therefore involve both HFS and LFS. Thiscould be done at ASDEX Upgrade where reflectometry systems are capable of measuring simultaneously thedensity turbulence on both HFS and LFS. The dependence between radial velocity, size and density of the blobsis also investigated.
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