S. Shiraiwa
A5005201278- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Engineering Applied Research
- Electromagnetic Launch and Propulsion Technology
- Antenna Design and Analysis
- Silicon Carbide Semiconductor Technologies
- Microwave Engineering and Waveguides
- Gyrotron and Vacuum Electronics Research
- Solar and Space Plasma Dynamics
- Physics of Superconductivity and Magnetism
- Atomic and Subatomic Physics Research
- Magnetic Bearings and Levitation Dynamics
- Electric Motor Design and Analysis
- Geomagnetism and Paleomagnetism Studies
- Particle physics theoretical and experimental studies
- Spacecraft and Cryogenic Technologies
- Metallurgical Processes and Thermodynamics
- Plasma and Flow Control in Aerodynamics
- Particle Accelerators and Free-Electron Lasers
Princeton Plasma Physics Laboratory
2009-2025
Princeton University
2009-2025
Plasma Technology (United States)
2013-2024
Fusion Academy
2013-2024
Fusion (United States)
2013-2024
Massachusetts Institute of Technology
2010-2020
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2016
CEA Cadarache
2016
The University of Texas at Austin
2015
Hefei Institutes of Physical Science
2014
The SPARC Toroidal Field Model Coil (TFMC) Program was a three-year effort between 2018 and 2021 that developed novel Rare Earth Barium Copper Oxide (REBCO) superconductor technologies then successfully utilized these to design, build, test first-in-class, high-field (∼20 T), representative-scale (∼3 m) superconducting toroidal field (TF) coil. program executed jointly by the MIT Plasma Science Fusion Center (PSFC) Commonwealth Systems (CFS) as technology enabler of pathway fusion energy,...
The SPARC Toroidal Field Model Coil (TFMC) is the first large-scale (∼3 m), high-field (∼20 T) superconducting fusion magnet based on Rare Earth Yttrium Barium Copper Oxide (REBCO). Its objective was to retire risk for toroidal field in tokamak, a burning plasma class magnetic confinement energy device. Weighing 10,058 kg and utilizing 270 km of REBCO, TFMC non-insulated, stack-in-plate style magnet. It has three main components: (1) winding pack; (2) structural case; (3) case extensions, or...
Abstract The objectives of NSTX-U research are to reinforce the advantages STs while addressing challenges. To extend confinement physics low- A , high beta plasmas lower collisionality levels, understanding transport mechanisms that set performance and pedestal profiles is being advanced through gyrokinetic simulations, reduced model development, comparison NSTX experiment, as well improved simulation RF heating. develop stable non-inductive scenarios needed for steady-state operation,...
The goal of the Lower Hybrid Current Drive (LHCD) system on Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] is to investigate current profile control under plasma conditions relevant future experiments. Experimental observations a LHCD "density limit" for are presented in this paper. Bremsstrahlung emission from relativistic fast electrons core drops suddenly above line averaged densities 1020 m−3 (ω/ωLH∼3–4), well below density limit previously observed other...
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...
The MIT Plasma Science and Fusion Center collaborators are proposing a high-performance Advanced Divertor RF tokamak eXperiment (ADX)-a specifically designed to address critical gaps in the world fusion research programme on pathway next-step devices: nuclear science facility (FNSF), pilot plant (FPP) and/or demonstration power (DEMO). This high-field (>= 6.5 T, 1.5 MA), high density (P/S similar MW m(-2)) will test innovative divertor ideas, including an 'X-point target divertor' concept,...
Abstract We explore the characteristics of EMIC waves generated in a non‐dipole, compressed magnetic field at minimum field. conducted 2D full‐wave simulations using Petra‐M code, focusing on outer dayside magnetosphere for range L values . By comparing simulation results with MMS observations, we aim to understand how observed wave are affected by shifting source region across different L‐shells. Our findings indicate that direction Poynting vector systematically changes depending local...
Experimental observations of lower hybrid current drive (LHCD) at high density on the Alcator C-Mod tokamak are presented in this paper. Bremsstrahlung emission from relativistic fast electrons core plasma drops suddenly above line-averaged densities 10 20 m −3 (ω/ω LH ∼ 3) single null discharges with large (⩾8 mm) inner gaps, well below limit previously observed limited tokamaks 2). Modelling and experimental evidence suggest that absence LHCD driven may be due to parasitic collisional...
Recent experiments on EAST have achieved the first long pulse H-mode (61 s) with zero loop voltage and an ITER-like tungsten divertor, demonstrated access to broad plasma current profiles by increasing density in fully-noninductive lower hybrid current-driven discharges. These discharges reach wall thermal particle balance, exhibit stationary good confinement (H98y2 ~ 1.1) low core electron transport, are only possible optimal active cooling of armors. In separate experiments, was...
Abstract For successfully heating plasma with waves in the Ion Cyclotron Range of Frequencies (ICRF), mitigating impurity production is just as crucial maximizing power coupling, especially high-Z environments [Urbanczyk 2021]. Only when coupled limited influence on production, can ICRF truly become a powerful tool to directly deposit energy ions, modify turbulence-driven transport and enhance efficiency fusion reactions. 
To do so, one must rely toroidal array at least three active...
Experiments in L- and H-mode plasmas performed on the DIII-D tokamak explored ion cyclotron emission (ICE) propagation via recently upgraded ICE diagnostic. The distance between plasma outer wall was scanned to alter evanescent region, which seen impact detection of runaway electron-driven whistler modes a comparable frequency range typical harmonics (f≳10fci) [Heidbrink et al., Plasma Phys. Controlled Fusion 61, 014007 (2018)]. In L-mode plasmas, core did not exhibit clear trends as...
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...
The possibility of plasma wave simulation based on the finite element method (FEM) was explored, and a new full code lower hybrid (LH) wave, Lower Hybrid wavE Analysis FEM (LHEAF), developed. efficient iterative solver for LH [O. Meneghini, S. Shiraiwa, R. Parker, Phys. Plasmas 16, 090701 (2009)] coupled to one-dimensional Fokker–Planck calculation obtain self-consistent distribution function. In LHEAF, seamless handling core, scrape off layer, antenna regions were realized launching...
In Alcator C-Mod discharges lower hybrid waves have been shown to induce a countercurrent change in toroidal rotation of up 60 km/s the central region plasma (r/a approximately <0.4). This modification profile develops on time scale comparable current redistribution (approximately 100 ms) but longer than energy and momentum confinement times 20 ms). A comparison co- injected indicates that drive (as opposed heating) is responsible for modifications. Furthermore, changes velocity induced by...
First principle modeling of the lower hybrid (LH) current drive in tokamak plasmas is a longstanding activity, which gradually gaining accuracy thanks to quantitative comparisons with experimental observations. The ability reproduce simulatenously plasma and non-thermal bremsstrahlung radial profiles hard x-ray (HXR) photon energy range represents this context significant achievement. Though subject limitations, ray tracing calculations are commonly used for describing wave propagation...
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 full wave simulation of the lower-hybrid (LH) based on finite element method is presented. For LH wave, most important terms dielectric tensor are cold plasma contribution and electron Landau damping (ELD) term, which depends only component vector parallel to background magnetic field. The nonlocal hot ELD effect was expressed as a convolution integral along field lines resultant integro-differential Helmholtz equation solved iteratively. propagation in Maxwellian tokamak Alcator C...
Ion cyclotron parametric decay instability (PDI) of lower hybrid (LH) waves is surveyed using edge Langmuir probes on the Alcator C-Mod tokamak. The measurement carried out simultaneously at high-field side (HFS) and low-field (LFS) mid-plane tokamak, as well in outer divertor region. Different LH spectra are observed depending location magnetic configuration L-mode plasmas, with drift direction downward. In single null (LSN) strong ion PDI occurring HFS for first time. This characterized by...
A numerical modeling of current profile modification by lower hybrid drive (LHCD) using a fullwave/Fokker-Planck simulation code is presented. MHD stable LHCD discharge on Alcator C-Mod was analyzed, and the from full wave simulations found to show better agreement with experiment than ray-tracing code. Comparison shows that, although can reproduce stochastic spectrum broadening, calculation predicts even wider fills all kinematically allowed domain. This first demonstration in multi-pass...
A newly developed generic electro-magnetic (EM) simulation tool for modeling RF wave propagation in SOL plasmas is presented. The primary motivation of this development to extend the domain partitioning approach incorporating arbitrarily shaped and antenna TORIC core ICRF solver, which was previously demonstrated 2D geometry [S. Shiraiwa, et. al., "HISTORIC: extending include realistic plasmas", Nucl. Fusion press], larger more complicated simulations by including a 3D integrating rectified...
Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to n¯e≈1.5×1020 m−3 in diverted plasmas on the Alcator C-Mod tokamak by operating increased plasma current—and therefore reduced Greenwald density fraction. This exceeds nominal “LH limit” n¯e≈1.0×1020 reported previously, above which an anomalous loss of efficiency was observed. The recovery a level consistent with engineering scalings correlated reduction shoulders and turbulence levels far scrape-off layer....
Abstract This paper reports a new numerical scheme to simulate the radio-frequency (RF) induced RF sheath, which is suitable for large 3D simulation. In sheath boundary model, tangential component of electric field ( <?CDATA $E_\mathrm{t}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>E</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">t</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) given by gradient scalar potential. We introduce two...
The MFEM (Modular Finite Element Methods) library is a high-performance C++ for finite element discretizations. supports numerous types of methods and the discretization engine powering many computational physics engineering applications across number domains. This paper describes some recent research development in MFEM, focusing on performance portability leadership-class supercomputing facilities, including exascale supercomputers, as well new capabilities functionality, enabling wider...
Following the application of lower hybrid current drive (LHCD) power, core toroidal rotation in Alcator C-Mod L- and H-mode plasmas is found to increment counter-current direction, conjunction with a decrease plasma internal inductance, l i . Along drops velocity, there peaking electron impurity density profiles, as well ion temperature profiles. The mechanism generating unknown, but it consistent sign an inward shift energetic orbits, giving rise negative radial electric field. density, (in...