A5090848931- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Fusion materials and technologies
- Engineering Applied Research
- Plasma Diagnostics and Applications
- Atomic and Subatomic Physics Research
- Physics of Superconductivity and Magnetism
- Nuclear reactor physics and engineering
- Piezoelectric Actuators and Control
- Innovative Energy Harvesting Technologies
- Welding Techniques and Residual Stresses
- Internet of Things and Social Network Interactions
- Frequency Control in Power Systems
- Industrial Vision Systems and Defect Detection
- Solar and Space Plasma Dynamics
- Manufacturing Process and Optimization
- Quantum chaos and dynamical systems
- Additive Manufacturing and 3D Printing Technologies
- Aeroelasticity and Vibration Control
- Soft Robotics and Applications
- Innovation in Digital Healthcare Systems
- Robotics and Automated Systems
Changwon National University
2012-2025
Mayo Clinic in Florida
2025
Jacksonville College
2025
Princeton Plasma Physics Laboratory
2015-2024
Princeton University
2008-2024
Seoul National University
2003-2024
Virginia Tech
2024
Korea Advanced Institute of Science and Technology
1999-2024
Chosun University
2005-2024
Korea Institute of Fusion Energy
2017-2022
A nominally axisymmetric plasma configuration, such as a tokamak or spherical torus, is highly sensitive to nonaxisymmetric magnetic perturbations due currents outside of the plasma. The high sensitivity means that primary interest in response very small perturbations, i.e., ∣b⃗∕B⃗∣≈10−2 10−4, which can be calculated using theory perturbed equilibria. ideal equilibrium code (IPEC) described and applied study torus external perturbations.
Abstract A fusion nuclear science facility (FNSF) could play an important role in the development of energy by providing environment needed to develop materials and components. The spherical torus/tokamak (ST) is a leading candidate for FNSF due its potentially high neutron wall loading modular configuration. key consideration choice configuration range achievable missions as function device size. Possible include: fluence, demonstrating tritium self-sufficiency, electrical self-sufficiency....
The application of static, non-axisymmetric, nonresonant magnetic fields (NRMFs) to high beta DIII-D plasmas has allowed sustained operation with a quiescent H-mode (QH-mode) edge and both toroidal rotation neutral beam injected torque near zero. Previous studies have shown that QH-mode can be accessed only if sufficient radial shear in the plasma flow is produced edge. In past experiments, this was using injection (NBI) provide torque. recent nearly completely replaced by from applied...
The sensitivity of tokamak plasmas to very small deviations from the axisymmetry magnetic field |deltaB/B| approximately 10{-4} is well known. What was not understood until recently importance perturbation plasma equilibrium in assessing effects externally produced asymmetries field, even far a stability limit. DIII-D and NSTX experiments find that when deleterious are mitigated, external asymmetric often made stronger had an increased interaction with unperturbed equilibrium. This Letter...
Small nonaxisymmetric perturbations of the magnetic field can greatly change performance tokamaks through nonambipolar transport. A number theories have been developed, but predictions were not consistent with experimental observations in tokamaks. This Letter provides a resolution, generalized analytic treatment It is shown that discrepancy between theory and experiment be reduced by two effects: (1) small fraction trapped particles for which bounce precession rates resonate; (2) variation...
The low-aspect ratio, low magnetic field and wide range of plasma beta NSTX plasmas provide new insight into the origins effects errors. An extensive array sensors has been used to analyse error fields, measure error-field amplification detect resistive wall modes (RWMs) in real time. measured normalized threshold for onset locked shows a linear scaling with density, weak inverse dependence on toroidal positive shear. These results extrapolate favourable ITER. For these low-beta locked-mode...
With the installation of non-axisymmetric coil systems on major tokamaks for purpose studying prospects ELM-free operation, understanding plasma response to applied fields is a crucial issue. Application different models, using standard tools, DIII-D discharges with from internal coils, shown yield qualitatively results. The can be treated as an initial value problem, following system dynamically unperturbed state, or nearby perturbed equilibrium approach, and both linear nonlinear models...
A tokamak relies on the axisymmetric magnetic fields to confine fusion plasmas and aims deliver sustainable clean energy. However, misalignments arise inevitably in construction, leading small asymmetries field known as error (EFs). The EFs have been a major concern approaches because EFs, even less than 0.1%, can drive plasma disruption. Meanwhile, be favorably used for controlling instabilities, such edge-localized modes (ELMs). Here we show an optimization that tailors maintain edge 3D...
Tokamaks are sensitive to deviations from axisymmetry as small δB/B0∼10−4. These nonaxisymmetric perturbations greatly modify plasma confinement and performance by either destroying magnetic surfaces with subsequent locking or deforming associated nonambipolar transport. The Ideal Perturbed Equilibrium Code (IPEC) calculates ideal perturbed equilibria provides important basis for understanding the sensitivity of tokamak plasmas perturbations. IPEC calculations indicate that response,...
A new method for correcting magnetic field errors in the ITER tokamak is developed using Ideal Perturbed Equilibrium Code. The dominant external driving islands shown to be localized outboard midplane three equilibria that represent projected range of operational scenarios. coupling matrices between poloidal harmonics perturbations and resonant fields on rational surfaces drive are combined different used determine an ordered list field. It found efficient robust error correction possible...
Tokamak plasmas become less tolerant to externally applied non-axisymmetric magnetic 'error' fields as beta increases, due a resonant interaction of the field with stable n = 1 kink mode. Similar observations in low plasmas, limit tolerable errors neutral beam injection heated H-mode is seen bifurcation torque balance, which followed by error field-driven locked modes and severe confinement degradation or disruption. The tolerance is, therefore, largely determined braking resulting from...
We report on a recent set of experiments performed in NSTX to explore the effects non-axisymmetric magnetic perturbations stability edge-localized modes (ELMs). The application these 3D fields was found have strong effect ELM stability, including destabilization ELMs H-modes otherwise free large ELMs. Exploiting perturbations, been controllably introduced into lithium-enhanced ELM-free H-modes, causing reduction impurity accumulation while maintaining high confinement. Although show...
The application of nonaxisymmetric magnetic fields is shown to destabilize edge-localized modes (ELMs) during otherwise ELM-free periods discharges in the National Spherical Torus Experiment (NSTX). Profile analysis shows applied increased temperature and pressure gradients, decreasing edge stability. This robust effect was exploited for a new form ELM control: triggering ELMs at will high performance H mode plasmas enabled by lithium conditioning, yielding time-averaged energy confinement...
Toroidal torque is one of the most important consequences non-axisymmetric fields in tokamaks. The well-known neoclassical toroidal viscosity (NTV) due to second-order force from anisotropic pressure tensor presence these asymmetries. This work shows that first-order originating same tensor, despite having no flux surface average, can significantly modify local perturbed balance and thus must be included equilibrium self-consistent with NTV. operator an not self-adjoint when NTV finite...
The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in summer of 2015.NSTX-U first plasma subsequently achieved, diagnostic control systems have been commissioned, H-mode accessed, magnetic error fields identified mitigated, physics research campaign carried out.During ten run weeks operation, NSTX-U surpassed record pulse-durations toroidal (TF), high-performance ~1 MA plasmas comparable to best sustained near...
Journal Article Judicial Independence and Retention Elections Get access Brandice Canes-Wrone, Canes-Wrone Princeton University Search for other works by this author on: Oxford Academic Google Scholar Tom S. Clark, Clark Emory Jee-Kwang Park The of Law, Economics, Organization, Volume 28, Issue 2, June 2012, Pages 211–234, https://doi.org/10.1093/jleo/ewq009 Published: 20 September 2010
The application of static magnetic field perturbations to a tokamak plasma is observed alter the dynamics high-frequency bursting Alfv\'en modes that are driven unstable by energetic ions. In response with an amplitude $\ensuremath{\delta}B/B\ensuremath{\sim}0.01$ at boundary, mode reduced, frequency increased, and chirp smaller. For weaker character, perturbation induces temporary transition saturated continuous mode. Calculations perturbed distribution function indicate 3D affects orbits...
Error field correction results in DIII-D plasmas are presented various configurations. In both left-handed and right-handed plasma configurations, where the intrinsic error fields become different due to opposite helical twist (handedness) of magnetic field, optimal currents toroidal phases internal(I)-coils empirically established. Applications Ideal Perturbed Equilibrium Code these demonstrate that component be minimized is not resonant external but total including ideal responses....
Experiments at DIII-D investigated the effects of magnetic error fields similar to those expected from proposed ITER test blanket modules (TBMs) containing ferromagnetic material. Studied were on: plasma rotation and locking, confinement, L–H transition, H-mode pedestal, edge localized modes (ELMs) ELM suppression by resonant perturbations, energetic particle losses, more. The experiments used a purpose-built three-coil mock-up two magnetized TBMs in one equatorial port. largest effect was...
Validating the calculations of kinetic resistive wall mode (RWM) stability is important for confidently predicting RWM stable operating regions in ITER and other high performance tokamaks disruption avoidance. Benchmarking Magnetohydrodynamic Resistive Spectrum—Kinetic (MARS-K) [Y. Liu et al., Phys. Plasmas 15, 112503 (2008)], Modification to Ideal Stability by Kinetic effects (MISK) [B. Hu 12, 057301 (2005)], Perturbed Equilibrium Nonambipolar Transport (PENT) [N. Logan 20, 122507 (2013)]...
Results from recent experiments demonstrate that quiescent H-mode (QH-mode) sustained by magnetic torque non-axisymmetric fields is a promising operating mode for future burning plasmas. Using n=3 to replace counter-Ip neutral beam injection (NBI), we have achieved long duration, counter-rotating QH-mode operation with NBI ranging up co-Ip values of 1-1.3 Nm. This 3 4 times the scaled ITER will have. These utilized an ITER-relevant lower single-null plasma shape and were done νped* βNped....
A newly developed plasma response model, combining the nonlinear two-fluid MHD code TM1 and toroidal GPEC run in ideal mode, quantitatively predicts narrow isolated q95 windows (Δq95 ∼ 0.1) of edge-localized mode (ELM) suppression by n = 1, 2, 3 resonant magnetic perturbations (RMPs) both DIII-D KSTAR tokamaks across a wide range parameters. The key physics that unites experimental observations our simulations is close alignment essential q-surfaces location top pedestal prior to an ELM....
For manufacturing components with thick plates, such as in the heavy equipment and shipbuilding industries, gas metal arc welding (GMAW) process is applied. Among that apply plate GMAW process, there are groove butt joints, which fabricated through multi-pass welding. Various qualities managed welding, root-pass weld controlled to ensure complete joint penetration (CJP). Currently, state of during visually, making it difficult confirm condition real time. Therefore, a need predict In this...