Plasma and Fusion Research
Online ISSN : 1880-6821
ISSN-L : 1880-6821
Volume 8
Showing 151-175 articles out of 175 articles from the selected issue
Regular Articles
  • Fumiko OTSUKA, Tohru HADA, Shunjiro SHINOHARA, Takao TANIKAWA, Takeshi ...
    2013 Volume 8 Pages 2406067
    Published: June 19, 2013
    Released: June 13, 2015
    JOURNALS FREE ACCESS
    We developed an electrodeless electric thruster that utilizes ion cyclotron resonance/ponderomotive acceleration (ICR/PA) for ion acceleration. We conducted test particle simulations to assess the thruster’s performance. We compared the thrusts obtained using argon (Ar) and helium (He) gas as propellants at the same mass flow rate. On the basis of a model that includes ion wall loss and ion-neutral collisions, we estimated the exhaust velocity and thrust. We found that He ions are less influenced by both ion wall loss and ion-neutral collisions than are Ar ions because the gyroradii of He ions are generally smaller than those of Ar ions and the ratio of the gyrofrequency to the collision frequency for He ions is larger than that for Ar ions. In addition, the exhaust velocities of He ions are larger than those of Ar ions, as predicted by the quasilinear theory and ponderomotive potential. Consequently, the thrust and specific impulse for He are larger than those for Ar.
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  • Hideki TOMITA, Fumitaka YAMASHITA, Yousuke YAMAMOTO, Haruna MINATO, Ku ...
    2013 Volume 8 Pages 2406095
    Published: August 15, 2013
    Released: June 13, 2015
    JOURNALS FREE ACCESS
    A compact neutron pinhole camera using nuclear emulsion has been developed as a neutrone mission profile monitor for energetic ion diagnostics in fusion plasma. We measured point-spread function of the neutron pinhole camera consists of a pinhole collimator made of tungsten alloy and stacked nuclear emulsions. Using a high-speed, automatic readout and recognition of recoiled proton tracks, point-spread function for 14 MeV neutron was clearly obtained.
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  • Yuichi TAMURA, Tomohiro UMETANI, Shin KUBO
    2013 Volume 8 Pages 2406102
    Published: August 15, 2013
    Released: June 13, 2015
    JOURNALS FREE ACCESS
    This paper proposes an Augmented Reality (AR) system to assist operation and maintenance tasks in an indoor environment, such as a nuclear fusion reactor and its building. AR is a technology that enhances real information by adding 3D virtual objects, images, sounds, or movies via a web camera. The AR system often uses “markers” such as QR code to detect the place where the virtual content should appear. However, these markers are unnatural and they can disturb the scenery. We propose an AR system that can detect natural markers, which provides AR content via a network. This system stores the information related to markers and virtual objects on a server. A device connected to this system automatically downloads this content so that the user can watch the AR content via a web camera. We add a real-time numerical simulation function that allows us to simulate physical phenomena by touching AR contents. It also enables us to observe simulation results by downloading a movie of numerical simulation results from the simulation server. Overall, this system allows us to watch the same content with multiple devices and to simulate physical phenomena using various parameters.
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  • Tatsuya UNIGAME, Tomohiro UMETANI, Yuichi TAMURA
    2013 Volume 8 Pages 2406120
    Published: September 26, 2013
    Released: June 13, 2015
    JOURNALS FREE ACCESS
    This paper proposes a method of developing an object shape model for a virtual assembly system using a combination of visual ID tags and three-dimensional (3D) natural feature points. The object shape model with its real size information is useful in large structures where maintenance robots are used to perform repetitive tasks. We developed the feature-point-based shape model by capturing visual ID tags and the feature points of the image with a monocular camera. The developed model can be used for the detection of the object against a background image and for an estimation of its 3D pose (position and orientation). To estimate the pose of the object using the proposed method, we assigned 3D feature points to the captured image using its scale-invariant feature transform features. The method can be applied to complex background images by using visual ID tags or constructing a feature point model. Our experimental results confirmed the feasibility of the proposed method.
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  • Masaharu MATSUMOTO, Hideyuki USUI, Masanori NUNAMI, Masao NAKAMURA, Ik ...
    2013 Volume 8 Pages 2406132
    Published: September 26, 2013
    Released: June 13, 2015
    JOURNALS FREE ACCESS
    A parallelized two-dimensional full particle-in-cell (PIC) simulations with an adaptive mesh refinement (AMR) technique for the interaction of solar wind with kinetic scale magnetosphere around a magnetic sail are conducted. For multi-scale simulations, the newly developed AMR-PIC code has a method to modify the grid size and time step interval of computational domain in the midst of the simulations temporally and locally. In the simulation results under the typical working condition introducing the AMR technique, it is shown that the direction of interplanetary magnetic field depend strongly on the magnetospheric configuration including electron dynamics and Alfven bow shock structure. Although more validation studies are needed, the AMR-PIC code shows the worth of development for multi-scale simulations.
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  • Keiichi KAMADA, Yukihiro SOGA, Shuhei ODAWARA, Ken MISAWA, Mitsuhiro Y ...
    2013 Volume 8 Pages 2406154
    Published: November 15, 2013
    Released: June 16, 2015
    JOURNALS FREE ACCESS
    A hybrid Bragg resonator with an advanced and a traditional Bragg reflectors was designed to develop the frequency selectivity of the free electron maser with frequency of 40 GHz using an intense relativistic electron beam. A normal Bragg resonator with two traditional Bragg reflectors was also designed for the same frequency. The interaction between a propagating wave and a quasi-cutoff mode in an advanced Bragg reflector was expected to provide higher frequency selectivity than a traditional Bragg reflector. In the cold test, the frequency resolution of the hybrid Bragg resonator was appeared to be ±0.05 GHz, while that of the normal one was ±0.5 GHz.
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  • Laila A. EL-GUEBALY
    2013 Volume 8 Pages 3404041
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    Electricity generating plants powered by fusion have long been envisioned as possessing inherent advantages for enhanced safety and benign environmental impact over the presently used fuels. However, fusion power plant designs developed to date tend to generate a sizable amount of mildly radioactive materials, compared to fission reactors. Proper handling of the anticipated quantities of activated materials is important to the future of fusion energy. The problem of handling such materials has been overlooked in many past fusion studies and/or relegated to the back-end as only a disposal issue. In fact, the geological disposal is not an environmentally attractive option. Here, we propose an integrated management strategy that can handle the sizable, mildly activated fusion materials and minimize the radwaste burden for future generations. More specifically, we propose recycling and clearing the majority of fusion activated materials, if technically and economically feasible, and avoiding the geological disposal option. Demo and power plant designs should consider recycling and clearance as much as practically possible. Internationally, numerous fission industries are currently developing advanced techniques for spent nuclear fuel reprocessing and several regulatory agencies have issued guidelines for the free release of clearable materials. Both developments will be of great importance to fusion.
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  • Max KARASIK, Yefim AGLITSKIY, Jason W. BATES, Denis G. COLOMBANT, Davi ...
    2013 Volume 8 Pages 3404042
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    Krypton-fluoride laser is an attractive inertial fusion energy driver from the standpoint of target physics. Target designs taking advantage of zooming, shock ignition, and favorable physics with KrF reach energy gains of 200 with sub-MJ laser energy. The designs are robust under 2D simulations. Experiments on the Nike KrF laser support the physics basis.
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  • Jean-Christophe CHANTELOUP, Antonio LUCIANETTI, Daniel ALBACH, Thierry ...
    2013 Volume 8 Pages 3404043
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    The European laser driven fusion project HiPER relies on kilojoule, nanosecond pulse trains with repetition rates close to 10 hertz and high wall-plug efficiency. We propose a scheme based on diode-pumped amplifiers using Yb3+:YAG ceramics as gain medium. An active mirror architecture where the high reflection coated side is cooled using a low pressure static Helium gas cell, is proposed.
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  • Matthew F. WOLFORD, John D. SETHIAN, Matthew C. MYERS, Frank HEGELER, ...
    2013 Volume 8 Pages 3404044
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    The United States Naval Research Laboratory is developing an electron beam pumped krypton fluoride laser technology for a direct drive inertial fusion energy power plant. The repetitively pulsed krypton fluoride laser technology being developed meets the fusion energy requirements for laser beam quality, wavelength, and repetition rate. The krypton fluoride laser technology is projected, based on experiments, to meet the requirements for wall plug efficiency and durability. The projected wall plug efficiency based on experiments is greater than 7 percent. The Electra laser using laser triggered gas switches has conducted continuous operation for 90,000 shots at 2.5 Hertz operation (ten hours). The Electra laser has achieved greater than 700 Joules per pulse at 1 and 2.5 Hertz repetition rate. The comparison of krypton fluoride laser performance with krypton fluoride kinetics code shows good agreement for pulse shape and laser yield. Development and operation of a durable pulse power system with solid state switches has achieved a continuous run of 11 million pulses into a resistive load at 10 Hz.
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  • Nobukazu KAMEYAMA, Hiroki YOSHIDA
    2013 Volume 8 Pages 3404045
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    We developed the permanent magnet array to separate a target from a sabot and analyzed the deceleration of the sabot velocity per unit length. The injection accuracy is about ± 12 mm at one meter from the injector muzzle when the sabot velocity is around 30 m/s. The method of compensation of a phase conjugate beam with four-wave mixing is shown. As one pump beam for four-wave mixing has a bit of longitudinal angle from the plane that another pump beam and a seed beam propagate, the phase conjugate beam tilts at the same angle from the plane. The displacement angle of the phase conjugate beam is compensated by adequately adjusting the angle between two pump beams.
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  • Yoneyoshi KITAGAWA, Yoshitaka MORI, Osamu KOMEDA, Katsuhiro ISHII, Ryo ...
    2013 Volume 8 Pages 3404047
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    A table-top fusion experiment is performed. A 4J/0.4-ns output of an LD-pumped high-rep. laser HAMA is divided into the imploding and heating beams, which are illuminated on double deuterated polystyrene foils separated by 100 µm. Hot electrons produced by the heating pulses heat the imploded core, emitting X-ray radiations >20 eV and yielding some 103 thermal neutrons. The result shows an important step toward developing the fast-ignition scheme fusion plant.
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  • Shigeo KAWATA, Tatsuya KUROSAKI, Shunsuke KOSEKI, Kenta NOGUCHI, Daisu ...
    2013 Volume 8 Pages 3404048
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF) by a spiraling beam axis motion. So far the wobbling heavy ion beam (HIB) illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may contribute to the reduction of the HIBs' illumination nonuniformity. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be several 100 MHz ∼ 1 GHz. Three-dimensional HIBs illumination computations presented here show that the few % wobbling HIBs illumination nonuniformity oscillates successfully with the same wobbling HIBs frequency.
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  • Kohei SUGITA, Hideaki MATSUURA, Yasuyuki NAKAO
    2013 Volume 8 Pages 3404050
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    In highly-compressed plasmas as realized in inertial confinement fusion, the wave nature of electrons becomes noticeable and Pauli's exclusion principle restricts the energy transition of electrons remarkably. Such a state is called “electron degeneracy”. In addition, the electron degeneracy may affect the energy distribution and temperature of coexisting ions through Coulombic ion-electron interaction. In order to evaluate these effects, we developed and solved the model equation for the distribution function of ions in degenerate electron plasmas. As a result, it is shown that the ion distribution function maintains a Maxwellian form at a temperature equal to that of degenerate electrons in thermal equilibrium because two effects of electron degeneracy—spectral hardening and Pauli blocking—counteract each other. Furthermore the electron degeneracy slows temperature relaxation between ions and electrons in non-thermal equilibrium.
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  • Paul D. MASON, Saumyabrata BANERJEE, Klaus ERTEL, P. Jonathan PHILLIPS ...
    2013 Volume 8 Pages 3404051
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    We present preliminary amplification results for DiPOLE, a prototype diode-pumped cryogenic gas cooled Yb:YAG amplifier. Amplification of ns-pulses at 1030 nm has demonstrated output energies of 10.1 J at 1 Hz in a 4-pass extraction geometry and 6.4 J at 10 Hz in a 3-pass setup, corresponding to optical-to-optical conversion efficiencies of 21% and 16%, respectively. Measured performance compares favourably to existing systems and confirms the viability of the concept for efficient generation of high energy pulses at multi-Hz repetition rate. Work is now underway to confirm the scalability of the concept with the design of a 100 J amplifier system. This along with advances in Ti:Sapphire amplifier technology opens the way to the development of a multi-Hz, PW-class laser facility at the Central Laser Facility. Knowledge gained from these developments will de-risk the technology necessary to build a sub-aperture beamlet for a laser driver suitable for fusion energy generation.
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  • Irina V. ALEKSANDROVA, Elena R. KORESHEVA, Eugeniy L. KOSHELEV, Igor E ...
    2013 Volume 8 Pages 3404052
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    In this report, we discuss the main building blocks and interface units of the FST supply system, layout algorithm and new results of the testing experiments. In this area, we firstly give a presentation of the FST approach to design and construction of the target supply system for HiPER project; describe possible ways of integration of our latest developments into engineering applications (e.g. FST-layering module with a double-spiral layering channel), and discuss the cost estimations of the FST supply system in the case of HIPER-scale targets.
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  • Koichi KASUYA, Wardemar MROZ, Boguslaw BUDNER, Shinji MOTOKOSHI, Katsu ...
    2013 Volume 8 Pages 3404054
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    A new method to estimate erosion threshold of various material surfaces with a high-power pulsed electron beam [Appendix] was extended to the surface erosions with various pulsed laser lights. The most interesting result was that the CVD polycrystalline diamond had similar erosion threshold as tungsten. After our extended experiments of this kind in the near future, novel plasma-facing surface materials are expected to be realized for future fusion reactor chambers.
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  • Jesus ALVAREZ, Kunioki MIMA, Kazuo A. TANAKA, Javier FERNANDEZ, David ...
    2013 Volume 8 Pages 3404055
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    Laser fusion environments are characterized by prompt bursts of high energy neutrons, ions and X-rays which are absorbed by different components of the fusion reaction chamber. In particular, plasma facing components are subjected to extreme conditions and prior to their use in the reactors they must be validated under stringent irradiation tests. However, the particular characteristics of the fusion products, i.e. very short pulses, very high fluences and broad particle energy spectra are difficult to reproduce in test laboratories, making those validations hard to be carried out. In the present work, the ability of ultraintense lasers to create the appropriate characteristics of laser fusion bursts is addressed. A description of a possible experimental set-up to generate the appropriate ion pulses with lasers is presented. At the same time, the possibility of generating X-ray or neutron beams which reproduce those of laser fusion environments is also pointed out and assessed under current laser intensities. It is concluded that ultraintense lasers should play a relevant role in the validation of materials for laser fusion facilities and immediate action for this systematic study is called for.
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  • Emilio MÍNGUEZ, Miguel A. MENDOZA, Rafael RODRÍGUEZ, Jesus G. RUBIANO, ...
    2013 Volume 8 Pages 3404056
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    The Atomic Physics Group at the Institute of Nuclear Fusion (DENIM) in Spain has accumulated experience over the years in developing a collection of computational models and tools for determining some relevant microscopic properties of, mainly, ICF and laser-produced plasmas in a variety of conditions. In this work several applications of those models in determining some relevant microscopic properties are presented.
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  • Vladimir D. ZVORYKIN, Andrei S. ALIMOV, Sergei V. ARLANTSEV, Boris S. ...
    2013 Volume 8 Pages 3405046
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    Several facilities are used to test trasmissive optics of the IFE target chamber and KrF laser driver in regard of transient and residual radiation-induced absorption in the range of 150-1200 nm. Comparative study of radiation darkening of various fused silica glasses, high-purity CaF2, MgF2, and Al2O3 crystals under irradiation by 300-keV electrons, soft ( = 6-20 keV) and hard ( ∼ 400 keV) X-rays is done and better radiation-proof optical materials are selected; the opposite effect of optics bleaching under UV laser light is observed.
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  • Daniel ALBACH, Thierry GONCALVES-NOVO, Jean-Christophe CHANTELOUP
    2013 Volume 8 Pages 3405049
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    Ceramic gain media are interesting candidates for large size gain media in high power diode pumped solid state lasers. We compare their performance to their crystalline counterparts used in the Lucia main amplifier. Small signal gain, wave front deformation and depolarization are of main interest.
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  • Masatoshi KONDO, Takeo MUROGA
    2013 Volume 8 Pages 3405053
    Published: May 22, 2013
    Released: May 19, 2014
    JOURNALS FREE ACCESS
    The corrosion characteristics of reduced activation ferritic martensitic steels, JLF-1 (Fe-9Cr-1.94W-0.09C) and 9Cr-ODS (Fe-9Cr-1.97W-0.14C-0.29Y-0.23Ti), and unalloyed metals of Cr, W and Mo in liquid Pb-17Li were investigated by means of static corrosion tests at 600C for 500 hours. The corrosion of the JLF-1 steel was based on the dissolution of Fe and Cr from the steel surfaces in the Pb-17Li. The dissolution type corrosion of the 9Cr-ODS steel was based on the strong depletion of Cr, W and O at the steel surface. The corrosion of the unalloyed Cr specimen in the Pb-17Li was much larger than that based on the Cr solubility in the Pb-17Li when a Mo crucible was used in the corrosion test. The corrosion was promoted under an unsaturated condition because the wetted surface of the Mo crucible trapped the dissolved Cr in the Pb-17Li by the alloying process. The dissolution of Mo in the Pb-17Li was also promoted by the alloying with the dissolved Cr though the solubility of Mo in the Pb-17Li was quite low. The weight loss of the unalloyed W specimen exposed in the Pb-17Li was larger than that estimated from the solubility in the Pb-17Li. Some oxide particles were detected on the surface of the W specimen. The reasonable mechanism on the large weight loss of the W specimen was the formation and detachment of the oxide particles in the Pb-17Li.
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Overview Articles
  • Tetsuya WATANABE, Hirohisa HARA, Norimasa YAMAMOTO, Daiji KATO, Hiroyu ...
    2013 Volume 8 Pages 2501105
    Published: August 15, 2013
    Released: June 16, 2015
    JOURNALS FREE ACCESS
    Spectroscopic observations of EUV emission lines in the transition region (TR) and the corona provide unique information on physical conditions in the outer atmosphere of the Sun. The EUV Imaging Spectrometer (EIS) on board the Hinode satellite is capable of observing, for the first time in EUV, spectra and monochromatic images of plasmas in the solar TR and corona; these plasmas could possibly be in non-ionization-equilibrium conditions. EIS observes over two-wavelength bands of 170-210 Å and 250-290 Å, with typical time-resolutions of 1-10 seconds. Iron line emissions emerging from these wavelengths reveal that dynamic plasma accelerations and heating take place in the solar atmosphere. On the other hand, the tracer-encapsulated-pellet (TESPEL) experiments provide spectral information of EUV emission lines from iron ions produced in the Large Helical Device (LHD). Relatively cool plasmas with electron temperatures similar to those of the solar corona can be generated by controlling the neutral beam injector (NBI) system. A time-dependent collisional radiative (CR) model for elemental iron is developed as a common tool to diagnose temperatures and densities of those plasmas in the Sun and in LHD; no systematic model yet exists for iron ions in the L- and M-shell ionization stages, which are very important for coronal plasma diagnostics. Adopting the best available theoretical calculations, as well as generating the experimental data, we improve the atomic parameters of highly charged iron ions, and these results are used to extract more accurate diagnostic information out of the EIS spectra.
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  • Vasily G. KIPTILY, Sergei E. SHARAPOV, Thomas GASSNER, Christian PEREZ ...
    2013 Volume 8 Pages 2502071
    Published: June 19, 2013
    Released: June 16, 2015
    JOURNALS FREE ACCESS
    Fast ion redistribution and losses caused by plasma disruptions, Toroidal Alfvén Eigenmodes (TAE) and fishbones are measured with a suite of improved gamma-ray diagnostics, Neutral Particle Analyser (NPA), neutron spectrometry, Faraday Cups and a Scintillator Probe (SP). Fast ion populations in the MeV energy range were generated in fusion reactions and were also produced by 3rd harmonic Ion Cyclotron Resonance Heating (ICRH). Significant fast ion losses preceding plasma disruptions were often detected by SP in discharges with high βN. These losses were caused by the m=2/n=1 kink mode and typically occurred at the time of thermal quench, before the current quench. Core-localised TAE modes inside the q=1 radius causing redistribution of the fast ions in the resonance energy range were directly measured for the first time with the gamma-ray camera, confirming that the TAE instability expels fast ions from inside the q=1 radius and triggers the monster sawtooth crashes. Energy and pitch angle resolved SP measurements of lost fusion products in the MeV energy range were found to correlate with low-frequency fishbone oscillations driven by 100 keV beam ions. The origin and amplitude of these non-resonant losses are investigated.
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  • Yuri RALCHENKO
    2013 Volume 8 Pages 2503024
    Published: April 23, 2013
    Released: June 16, 2015
    JOURNALS FREE ACCESS
    We present an overview of the recent advances in collisional-radiative modeling of highly-charged ions of tungsten that are relevant to fusion research. The status of spectroscopic data for W ions is briefly discussed as well. Strategies and peculiarities of building models for Maxwellian fusion plasmas and non-Maxwellian plasmas of electron beam ion traps are outlined. Comparisons with the measured x-ray and extreme ultraviolet spectra are also given.
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