A5070196881- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Astro and Planetary Science
- Spacecraft and Cryogenic Technologies
- Geomagnetism and Paleomagnetism Studies
- Laser-induced spectroscopy and plasma
- Electromagnetic Launch and Propulsion Technology
- Gamma-ray bursts and supernovae
- Distributed and Parallel Computing Systems
- Geophysics and Gravity Measurements
- Nuclear reactor physics and engineering
- Advanced Thermodynamic Systems and Engines
- Atomic and Subatomic Physics Research
- Astronomy and Astrophysical Research
- Particle Accelerators and Free-Electron Lasers
- Combustion and Detonation Processes
- Heat Transfer and Optimization
- Planetary Science and Exploration
- Magnetic Field Sensors Techniques
- Semiconductor materials and devices
- Particle Detector Development and Performance
University of Wisconsin–Madison
1997-2025
The Pegasus Toroidal Experiment was developed to explore the physics limits of plasma operation as aspect ratio (A) approaches unity. Initial experiments on device found that access high normalized current and toroidal beta limited by presence large-scale tearing modes. Major upgrades have been conducted facility provide control tools necessary mitigate these resistive include new programmable power supplies, poloidal field coils increased, time-variable field. First ohmic operations with...
Initiating current without using magnetic induction from a central solenoid is critical scientific and technical challenge facing the spherical tokamak (ST). One such technique that has shown promise on several devices coaxial helicity injection (CHI). In CHI, dc voltage applied to large area electrodes injects into vacuum vessel for plasma startup ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{p}$...
Developing attractive means of initiating current without using magnetic induction from a central solenoid is critical scientific and technical challenge facing the spherical tokamak (ST). The PEGASUS program has focused on developing physics basis predictive models for nonsolenoidal startup local helicity injection (LHI) demonstrated to ~0.2 MA in low-field, near-unity aspect ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">...
Research on the spherical torus (or tokamak) (ST) is being pursued to explore scientific benefits of modifying field line structure from that in more moderate aspect ratio devices, such as conventional tokamak. The ST experiments are conducted various US research facilities including MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium sized facilities: PEGASUS University Wisconsin, HIT-II Washington, CDX-U Princeton. In context fusion energy development path...
Measurements of the internal distribution B in magnetically confined plasmas are required to obtain current profiles via equilibrium reconstruction with sufficient accuracy challenge stability theory. A 16-channel linear array InSb Hall effect sensors 7.5 mm spatial resolution has been constructed directly measure B(z)(R,t) for determination J(ψ,t) associated edge-localized peeling mode instabilities Pegasus Toroidal Experiment. The diagnostic is mounted an electrically isolated vacuum...
The Pegasus Toroidal Experiment [R. Fonck et al., Bull. Am. Phys. Soc. 41, 1400 (1996)] is a spherical torus designed to study the limits of plasma behavior as aspect ratio A approaches unity. Access near-unity achieved through use novel high-stress reinforced solenoid magnet. High toroidal beta βt obtained in ohmically-heated plasmas by operation at low field with densities up Greenwald limit. Values 20% and normalized 5 have been obtained. current rod current, known utilization, reaches...
The PEGASUS-III experiment is a solenoid-free, low aspect ratio spherical tokamak that will serve as dedicated U.S. platform for comparative nonsolenoidal plasma startup studies. Approximately 175 megavolt-ampere (MVA) of reconfigured and expanded programmable power systems, 7 MJ new stored energy, digital control protection systems the facility are being commissioned to support upgrades. These include: increased toroidal field (0.15–0.6 T); divertor poloidal coils; pulse length; local...
An optical neutral beam spectroscopy system is being designed to provide equilibrium and stability measurements for the PEGASUS toroidal experiment. Spatially localized of electron temperature plasma density are possible by observing intensity collisionally induced fluorescence. In a helium beam, population singlet levels relatively independent compared triplet levels. Therefore, ratio intensities transition (e.g., 33S→23P, λ=706.5 nm) 31P→21S, λ=501.6 provides measure local range 10...