A5082092397- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Gyrotron and Vacuum Electronics Research
- Seismic Imaging and Inversion Techniques
- Scientific Computing and Data Management
- Nuclear reactor physics and engineering
- Electromagnetic Launch and Propulsion Technology
- Electric Motor Design and Analysis
- Physics of Superconductivity and Magnetism
- Electromagnetic Simulation and Numerical Methods
- Advanced MRI Techniques and Applications
- Advanced Data Storage Technologies
- Research Data Management Practices
- Acoustic Wave Resonator Technologies
- Geomagnetism and Paleomagnetism Studies
- Atomic and Molecular Physics
- Dust and Plasma Wave Phenomena
- High voltage insulation and dielectric phenomena
Massachusetts Institute of Technology
2015-2024
Plasma Technology (United States)
2015-2024
Fusion Academy
2014-2024
Fusion (United States)
2013-2024
United Kingdom Atomic Energy Authority
2022
Culham Science Centre
2017-2022
Oak Ridge National Laboratory
2009-2020
University of California, Los Angeles
2020
Lodestar Research Corporation (United States)
2011-2020
Royal Military Academy
2020
The SPARC tokamak is a critical next step towards commercial fusion energy. designed as high-field ( $B_0 = 12.2$ T), compact $R_0 1.85$ m, $a 0.57$ m), superconducting, D-T with the goal of producing gain $Q>2$ from magnetically confined plasma for first time. Currently under design, will continue path Alcator series tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in device. achievable conservative...
Abstract The SPARC tokamak project, currently in engineering design, aims to achieve breakeven and burning plasma conditions a compact device, thanks new developments high-temperature superconductor technology. With magnetic field of 12.2 T on axis 8.7 MA current, is predicted produce 140 MW fusion power with gain Q ≈ 11, providing ample margin respect its mission > 2. All systems are being designed this landmark discharge, thus enabling the study physics operations reactor relevant pave...
To examine interhemispheric interactions of motor processes by using functional MRI (fMRI).Despite evidence inhibition from animal, clinical, and transcranial magnetic stimulation (TMS) studies, fMRI has not been used to explore activation deactivation during unilateral tasks. changes associated with activity have traditionally described comparing cerebral tasks relative a "resting state." In addition this standard comparison, we examined in the resting state task.Thirteen healthy volunteers...
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...
SPARC is designed to be a high-field, medium-size tokamak aimed at achieving net energy gain with ion cyclotron range-of-frequencies (ICRF) as its primary auxiliary heating mechanism. Empirical predictions conservative physics indicate that baseline plasmas would reach $Q\approx 11$ , which well above mission objective of $Q>2$ . To build confidence will successful, physics-based integrated modelling has also been performed. The TRANSP code coupled the theory-based trapped gyro-Landau...
This paper summarizes the physical principles behind novel three-ion scenarios using radio frequency waves in ion cyclotron range of frequencies (ICRF). We discuss how to transform mode conversion electron heating into a new flexible ICRF technique for and fast-ion generation multi-ion species plasmas. The theoretical section provides practical recipes selecting plasma composition realize scenarios, including two equivalent possibilities choice resonant absorbers that have been identified....
Lower hybrid (LH) waves (Ωci⪡ω⪡Ωce, where Ωi,e≡Zi,eeB/mi,ec) have the attractive property of damping strongly via electron Landau resonance on relatively fast tail electrons and consequently are well-suited to driving current. Established modeling techniques use Wentzel–Kramers–Brillouin (WKB) expansions with self-consistent non-Maxwellian distributions. Higher order WKB shown some effects parallel wave number evolution due diffraction [G. Pereverzev, Nucl. Fusion 32, 1091 (1991)]. A...
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...
Ion cyclotron range of frequencies (ICRF) heating will be the sole auxiliary method on SPARC for both full-field ( B t 0 ~ 12 T) D–T operation and reduced field 8 D–D operation. Using fast wave at ~120 MHz, good penetration strong single-pass absorption is expected D–T( 3 He), D( D(H) 4 He(H) scenarios. The dependences ${k_\parallel }$ , He concentration, resonance location, antenna poloidal location losses alpha particles ash have been studied. loading has assessed by comparison with...
Fast wave (FW) studies of mode conversion (MC) processes at the ion–ion hybrid layer in toroidal plasmas must capture disparate scales FW and converted ion Bernstein cyclotron waves. Correct modeling MC requires resolving wavelengths on order k⊥ρi∼1 which leads to a scaling maximum poloidal number, Mmax, proportional 1/ρ* (ρ*≡ρi/L). The computational resources needed scale with number radial (Nr), (Nθ), (Nφ) elements as Nr * Nφ Nθ3. Two full codes, massively-parallel-processor (MPP) version...
This paper reviews the physics and technology of wave-particle-interaction experiments in ion cyclotron range frequencies (ICRF) lower hybrid (LH) (LHRF) on Alcator C-Mod tokamak. Operation fixed frequency (80 MHz) tunable (40- to 80-MHz) ICRF transmitters associated transmission system is described. Key fabrication issues that were solved order operate a four-strap antenna compact environment are discussed some detail. heating utilizing hydrogen (H) helium-3 (3He) minority schemes...
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...
Recent achievements in studies of the effects ICRF (Ion Cyclotron Range Frequencies) power on SOL (Scrape-Off Layer) and PWI (Plasma Wall Interactions) ASDEX Upgrade (AUG), Alcator C-Mod, JET-ILW are reviewed. Capabilities to diagnose model effect DC biasing associated impurity production at active antennas magnetic field connections described. The experiments show that near-fields can lead not only E × B convection, but also modifications density, which for C-Mod limited a narrow region...
A two-dimensional integral full-wave model is used to calculate poloidal forces driven by mode conversion in tokamak plasmas. In the presence of a magnetic field, near ion-ion hybrid resonance dominated transition from fast magnetosonic wave slow ion cyclotron wave. The field generates strong variations parallel spectrum that cause damping narrow layer surface. resulting this drive sheared flows comparable those direct launch Bernstein experiments.
Lower hybrid (LH) current drive experiments have been carried out on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] using a radio-frequency system at 4.6GHz. Up to 900kW of LH power has coupled and driven currents inferred from magnetic measurements by extrapolating zero loop voltage, yielding an efficiency neILHR0∕PLH≈2.5±0.2×1019(A∕W∕m2). We simulated in these discharges combined ray tracing/three-dimensional (r,v⊥,v∥) Fokker–Planck code GENRAY-CQL3D (R....
Scattering effects induced by edge density fluctuations on lower hybrid (LH) wave propagation are investigated. The scattering model used here is based the work of Bonoli and Ott (1982 Phys. Fluids 25 361). It utilizes an electromagnetic kinetic equation solved a Monte Carlo technique. This has been implemented in GENRAY, ray-tracing code which explicitly simulates propagation, as well collisionless collisional damping processes, over entire plasma discharge, including scrape-off layer that...
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...
At modest H3e levels (n3He/ne∼8%–12%), in relatively low density D(H3e) plasmas, n¯e≤1.3×1020 m−3, heated with 50 MHz rf power at Bt0∼5.1 T, strong (up to 90 km/s) toroidal rotation (Vϕ) the cocurrent direction has been observed by high-resolution x-ray spectroscopy on Alcator C-Mod. The change central Vϕ scales applied (≤30 km s−1 MW−1), and is generally least a factor of 2 higher than empirically determined intrinsic plasma scaling. inner (r/a≤0.3) responds more quickly that outer region...
The next step toward fusion as a practical energy source is the design and construction of ITER [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)], device capable producing controlling high-performance plasma required for self-sustaining reactions, i.e., “burning plasma.” relies in part on ion-cyclotron radio frequency power to heat deuterium tritium fuel temperatures. In order effectively, wave fields must couple efficiently dense core plasma. Calculations this paper support argument that will...
Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that onset of perpendicular propagation right at or very near launcher is a primary cause for reduction in core efficiency long wavelengths also observed ICRF experiments numerous tokamaks. A dramatic increase was first achieved L-mode helium majority plasmas when moved away from antenna nearby vessel structures. Efficient deuterium H-mode discharges, which edge...
On the Alcator C-Mod tokamak, lower hybrid current drive (LHCD) is being used to modify profile with aim of obtaining advanced tokamak (AT) performance in plasmas parameters similar those that would be required on ITER. To date, power levels excess 1 MW at a frequency 4.6 GHz have been coupled into variety plasmas. Experiments established LHCD behaves globally as predicted by theory. Bulk efficiencies, n 20 I lh R / P ∼ 0.25, inferred from magnetics and MSE are line Quantitative comparisons...