Effects of low particle fuelling and electron heating on the internal transport barrier in ICRF heated reversed magnetic shear plasmas of JT-60U
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Plasmas with an internal transport barrier (ITB) were heated with a second-harmonic ion cyclotron range of frequency (ICRF) minority heating during the reversed magnetic shear (RS) experiments in JT-60U. In order to control the central particle fuelling, the input power of the neutral beam injection (NBI) heating during ICRF heating was scanned shot-by-shot. The electron temperature gradient around the ITB increased with the total input power. Steeper gradients were obtained with additional ICRF heating by avoiding collapses induced by the steep pressure gradient. The difference of the time derivative at the ICRF injection timing indicated a fast ion loss of about 40% during the RS operation. The density gradient was increased with the central fuelling by the NBI heating and the shoulder position of the slope at the ITB moved outward with the particle fuelling. The particle confinement time at the ITB increased with the central particle fuelling while the particle confinement time of the low-fuelling discharges were similar to that of the normal shear L-mode discharge.Keywords:
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Basic properties of the plasma edge in magnetically confined fusion plasmas are summarised. Starting from the magnetic topology of tokamaks we describe the transport of the scrape-off layer including drifts and the consequences of the electrostatic Debye sheath in front of the plasma facing components. The relation between the local plasma density and temperature at the targets and the fluxes of power and particles in the SOL is discussed. The transport of the fuel neutrals (hydrogen atoms and molecules) is described.
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Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation D. D. Ryutov; Magnetized Target Fusion With Centimeter‐Size Liners. AIP Conf. Proc. 5 January 2006; 808 (1): 329–334. https://doi.org/10.1063/1.2159382 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search
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A method for the energy analysis of electrons in the presence of trapped electrons has been developed. This was actually applied to measurements of electron distribution functions, including both free and trapped electrons in shock experiments. Finally, it was found from comparing the characteristic curves that this method has a great advantage over the probe technique for the purpose described above.
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Plasma transport is a phenomenon in which plasma particles and heat go from the plasma center to the periphery across the magnetic surface. This chapter discusses plasma transport and confinement and resulting constraints on the operation range. Plasma transport and confinement are important for maintaining the stability of fusion reaction. Experiments on magnetic confinement have shown that various instabilities exist in plasma. Scaling laws of energy confinement time have been obtained based on data of plasma experiments in the world. Various types of edge localized mode (ELM) have been observed in experiments and ELM can be classified from detailed temperature and density profile measurement and stability analysis of the edge plasma. The Greenwald density limit has been derived from the database of Joule-heating plasma. As high-energy particles, α particles are generated by the deuterium, tritium reaction. It is necessary to confine the α particles in the plasma until they are thermalized and heat plasma efficiently.
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Following the scheme of ${\mathrm{Hund}}^{1}$ for similar $s$, $p$ and $d$ electrons the terms arising from similar $f$ electrons have been worked out and tabulated. Tables have also been prepared for one and two electrons, where in the latter case these electrons are dissimilar i.e. have either different total or different azimuthal quantum numbers, and also for three electrons two of which are similar. These tables along with those for similar $s$, $p$ and $d$ electrons are found not only to be of frequent use but also to bring out certain rules that may be applied in determining spectral terms arising from any electron configuration.
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Abstract The dynamics of ultrarelativistic axially channeled electrons in thick crystals is studied. It is revealed that a certain fraction of initial electrons have anomalously large dechanneling depths. It is shown also that the dechanneling depth in heavy and light crystals are comparable. In some cases, the number of channeled electrons can strongly increase at the expence of quasi-channeled electrons. The problem of quasichanneling is also considered.
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Summary form only given, as follows. Multipolar plasma chambers have widely been used for research on basic and applied researches on low temperature plasmas. The multipolar confinement realizes enhanced plasma density, homogeneous plasma of a large volume, and quiescent plasmas. However, detailed theoretical studies on the multipolar confinement are few.
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Solid-state physics
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Langmuir or electrostatic probes are one of the oldest and yet the most widely used diagnostic in almost all fields of plasma physics research. Probe theories are, however, rather complex subject and invariably difficult to be experimentally checked with precision, even within the expected range of their validity. Testing probe theories against data from dedicated experiments using quiescent magnetized plasmas, is a very important task for assuring compatibility with the use of this diagnostic and validated models in more complex plasmas, notably those at the edge of the magnetic fusion plasmas. In these particular plasmas, attaining more precise plasma parameters directly impacts studies on a high variety of edge profile dependent phenomena, with impact in particle and heat transport and global confinement and local stability (e.g. H-mode pedestal and ELMs, respectively). It also helps to properly back-up more complex plasma edge diagnostics. The present work reports experiments to proper infer plasma parameters in low-magnetized glow discharge plasmas using electrostatic probes with different pin diameters, and operating in sweep mode. Particularly the plasma density parameter is detailed analyzed and inferred from different finite-plasma sheath theories, notably that from the non-magnetized collisioness plasma model proposed by Hutchinson.
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