A5007226541- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Atomic and Subatomic Physics Research
- Solar and Space Plasma Dynamics
- Gyrotron and Vacuum Electronics Research
- Nuclear Physics and Applications
- Dust and Plasma Wave Phenomena
- Ion-surface interactions and analysis
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- Advanced Frequency and Time Standards
- Physics of Superconductivity and Magnetism
- Laser Design and Applications
- Metallurgical Processes and Thermodynamics
- Nuclear reactor physics and engineering
- Magnetic Field Sensors Techniques
- Metal and Thin Film Mechanics
- Engineering Applied Research
- Spacecraft and Cryogenic Technologies
Tokamak Energy (United Kingdom)
2022-2023
The University of Tokyo
2013-2022
Princeton Plasma Physics Laboratory
1991-2021
Kyushu University
2005-2021
University of Wisconsin–Madison
1991-2021
National Institutes for Quantum Science and Technology
2021
Edgewood College
2021
Tokyo University of Science
2000-2019
Kyushu Tokai University
2005-2017
Kyoto University
2010-2017
Early operation of the Alcator-C-MOD tokamak [I.H. Hutchinson, Proceedings IEEE 13th Symposium on Fusion Engineering, Knoxville, TN, edited by M. Lubell, Nestor, and S. Vaughan (Institute Electrical Electronic Engineers, New York, 1990), Vol. 1, p. 13] is surveyed. Reliable operation, with plasma current up to 1 MA, has been obtained, despite massive conducting superstructure associated error fields. However, vertical disruptions are not slowed long vessel time constant. With pellet fueling,...
A series of pellet-fueling experiments has been carried out on the Alcator $C$ tokamak. High-speed hydrogen pellets penetrate to within a few centimeters magnetic axis, raise plasma density, and produce peaked density profiles. Energy confinement is observed increase over similar discharges fueled only by gas puffing. In this manner record values electron pressure, Lawson number ($n\ensuremath{\tau}$) have achieved.
A series of experiments, examining the confinement properties ion cyclotron range frequencies (ICRF) heated H mode plasmas, has been carried out on Alcator C-Mod tokamak. is a compact tokamak that operates at high particle, power and current densities toroidal fields up to 8 T. Under these conditions plasma essentially thermal with very little contribution stored energy from energetic ions (typically no more than 5%) Ti~Te. Most data were taken machine in single null `closed' divertor...
Regimes of high-confinement mode have been studied in the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. with no edge localized modes (ELM-free) compared detail to a new regime, enhanced Dα (EDA). EDA discharges only slightly lower energy confinement than comparable ELM-free ones, but show markedly reduced impurity confinement. Thus do not accumulate impurities and typically fraction radiated power. The gradients seem be relaxed by continuous process rather an...
The object of this review is to summarize the achievements research on Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994) and Marmar, Fusion Sci. Technol. 51, 261 (2007)] place that in context quest for practical fusion energy. a compact, high-field tokamak, whose unique design operating parameters have produced wealth new important results since it began operation 1993, contributing data extends tests critical physical models into parameter ranges regimes. Using only...
Abstract Ion temperatures of over 100 million degrees Kelvin (8.6 keV) have been produced in the ST40 compact high-field spherical tokamak (ST). excess 5 keV not previously reached any ST and only obtained much larger devices with substantially more plasma heating power. The corresponding fusion triple product is calculated to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>n</mml:mi> <mml:mi>i</mml:mi> <mml:mn>0</mml:mn>...
Impurity toroidal rotation has been observed in the centre of Alcator C-Mod ion cyclotron range frequencies (ICRF) heated plasmas, from Doppler shifts argon X ray lines. Rotation velocities greater than 1.2 × 107 cm/s (ω = 200 krad/s) co-current direction have H mode discharges that had no direct momentum input. There is a correlation between increase central impurity velocity and plasma stored energy (confinement enhancement), induced by ICRF heating, although other factors may be at play....
Recent experiments (Synakowski et al 2004 Nucl. Fusion 43 1648, Lloyd Plasma Phys. Control. 46 B477) on the Spherical Tokamak (or Torus, ST) (Peng 2000 Plasmas 7 1681) have discovered robust plasma conditions, easing shaping, stability limits, energy confinement, self-driven current and sustainment. This progress has encouraged an update of conditions engineering a Component Test Facility (CTF), (Cheng 1998 Eng. Des. 38 219) which is very valuable step in development practical fusion energy....
Two types of electrostatic modes with small-poloidal wave numbers ($\ensuremath{\sim}1$ and $10--15\text{ }\text{ }\mathrm{kHz}$) are observed in the edge region Ohmically heated plasmas JFT-2M tokamak. The envelope higher frequency coherent mode is modulated at lower mode. A bispectral analysis revealed that a significant nonlinear coupling among two fluctuations broadband background turbulent potential occurs inside last closed magnetic flux surface, suggesting process such as...
A quasi-steady-state lower-hybrid current-drive operation is demonstrated in the Alcator $C$ tokamak at densities up to ${\stackrel{-}{n}}_{e}\ensuremath{\simeq}1\ifmmode\times\else\texttimes\fi{}{10}^{14}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. The efficiency measured experimentally over a wide range of and magnetic fields. radial distribution high-energy x rays indicates that current-carrying electrons peak near plasma axis.
Abstract ST40 is a compact, high-field ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mi mathvariant="normal">T</mml:mi> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mtext>⩽</mml:mtext> <mml:mn>2.1</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mtext>T</mml:mtext> </mml:math> ) spherical tokamak (ST) with mission to expand the physics and technology basis for ST route commercial fusion. The research programme covers...
Parametric decay processes have been studied using rf probes and CO2 laser scattering during the lower-hybrid wave heating current drive experiments in Alcator C tokamak. The most important process is believed to be nonresonant into ion-cyclotron quasimodes and/or that electron-Landau quasimodes. At lower densities ω0/ωlh(0)&gt;2 [where ω0 frequency of injected pump ωlh(0) evaluated at plasma center], where efficient electron are obtained, parametric absent or very weak. higher...
QUEST focuses on the steady state operation of spherical tokamak by controlled PWI and electron Bernstein wave current drive. One main purposes is an achievement long duration discharge with MW-class injected power. As result, should be operated in challenging region heat particle handling. To do handling, high temperature all metal wall up to 623 K closed divertors are planned, which realize steady-state under recycling ratio, R = 1. This a dispensable check DEMO, because pumping avoided as...
Fully non-inductive second (2nd) harmonic electron cyclotron (EC) plasma current ramp-up was demonstrated with a newlly developed 28 GHz system in the QUEST spherical tokamak. A high of 54 kA non-inductively ramped up and sustained stably for 0.9 s 270 kW wave. higher 66 also achieved slow vertical field. We have significantly than those previously 2nd EC waves. This fully method might be useful future burning devices fusion reactors, particular operations at half magnetic field same heating...
Detailed measurements and transport analysis of divertor conditions in Alcator C-Mod [Phys. Plasmas 1, 1511 (1994)] are presented for a range line-averaged densities, 0.7&lt;n̄e&lt;2.2×1020 m−3. Three parallel heat regimes evident the scrape-off layer: sheath-limited conduction, high-recycling divertor, detached which can coexist same discharge. Local cross-field pressure gradients found to scale simply with local electron temperature. This scaling is consistent classical conduction...
A new spherical tokamak, TST-2, was constructed at the University of Tokyo and started operation in September 1999. Reliable plasma initiation is achieved with typically 1 kW ECH power 2.45 GHz. Plasma currents up to 90 kA toroidal fields 0.2 T have been during initial experimental campaign. The ion temperature 100 eV. Internal reconnection events are often observed. internal magnetic field measured r/a = 2/3 indicated growth fluctuations fourth harmonic, suggesting existence modes several...
Fully non-inductive plasma maintenance was achieved by a microwave of 8.2 GHz and 40 kW for more than 1 h 55 min with well-controlled plasma-facing wall (PFW) temperature 393 K, using hot in the middle-sized spherical tokamak QUEST, until discharge finally terminated uncontrollability density. The PFW composed atmospheric plasma-sprayed tungsten stainless steel. plays an essential role reducing amount wall-stored hydrogen facilitates recycling. behaviour fuel investigated monitoring...
Enhanced confinement modes up to a toroidal field of BT=8 T have been studied with 3.5 MW radiofrequency (rf) heating power in the ion cyclotron range frequencies (ICRF) at 80 MHz. H-mode is observed when edge temperature exceeds threshold value. The high mode (H-mode) higher enhancement factors (H) and longer duration became possible after boronization by reducing radiated from main plasma. A quasi-steady state (H=2.0), normalized beta (βN=1.5), low fraction (Pradmain/Ploss=0.3), effective...
The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high βT in order advance spherical torus (ST) concept. In do this, NSTX utilizes up 7.5 MW neutral beam injection, 6 harmonic fast waves (HHFWs), it operates with plasma currents 1.5 MA elongations 2.6 a field 0.45 T. New facility, diagnostic modelling capabilities developed over past two years have enabled research team make significant progress...
Experiments aiming at 'day long operation high performance' have been carried out in TRIAM-1M. The record value of the discharge duration was updated to 5 h and 16 min. Steady-state tokamak is studied under localized plasma wall interaction conditions. distributions heat load, particle recycling flux impurity source are investigated understand co-deposition pumping. formation sustainment an internal transport barrier (ITB) enhanced current drive mode has by controlling lower hybrid driven...
A new operational scenario of advanced tokamak formation was demonstrated in the JT-60U tokamak. This accomplished by electron cyclotron and lower hybrid waves, neutral beam injection, loop voltage supplied vertical field shaping coils. The Ohmic heating (OH) solenoid not used but a small inboard coil (part coil), providing less than $20%$ total poloidal flux, used. plasma thus obtained had both internal edge transport barriers, with an energy confinement time 1.6 times H-mode scaling, beta...
A review of TFTR plasma transport studies is presented. Parallel and the confinement suprathermal ions are found to be relatively well described by theory. Cross-field thermal plasma, however, anomalous with momentum diffusivity being comparable ion larger than electron in neutral beam heated discharges. Perturbative experiments have studied nonlinear dependencies coefficients examined role possible nonlocal phenomena. The underlying turbulence has been using microwave scattering, emission...
The results and interpretation of the modest-power (∼90 kW) lower-hybrid-heating experiment on Alcator A are presented. expected from linear waveguide-plasma coupling theory outlined, possible effects parametric instabilities, scattering density fluctuations, imperfect energetic ion confinement addressed. It is found experimentally that good absence RF breakdown achieved with a double waveguide array at available power densities PRF ≤ 4.5 kW.cm·−2, vacuum windows being outside toroidal field...