Current HSX Graduate Students
- Alexis Briesemeister
- Alexis is exploring the effects of quasi-symmetry on flows. To do this she led the implementation of a charge exchange recombination spectroscopy (ChERS) system on HSX. Her research is now focused on improving the ChERS system and using it to measure plasma flow velocity, ion temperature, and impurity ion density profiles. The radial electric field, which can be deduced from flow and pressure gradient measurements, will be compared to the values predicted by neoclassical theory.
- Chris Clark
- Chris is currently investigating impurity transport in the HSX Stellarator. He is leading the development and construction of a laser blow-off impurity injection system.
- In 2008, he led efforts to improve operations of HSX by controlling heavy impurity influx. This was first done through the use of a carbon limiter probe, and later through vessel carbonization. These efforts were somewhat effective, but were supplanted by much more effective Boronization in 2009.
- In 2007, he developed a computer simulation and data analysis program for a novel form of heavy ion beam probe.
- In 2006, he succesfully verified the predicted axis shift between Mirror and QHS modes by developing and operating an electron beam probe diagnostic.
- Jerahmie Radder
- Area - rf heating and design and fabrication of a quasi-optical launching system for the high-power electron cyclotron resonance heating microwaves - 2 gyrotrons, 200 kilowatts each, for 50 to 75 milliseconds.
- Laurie Stephey
- Laurie is currently studying plasma fueling and the HSX neutral polulation. She uses H-Alpha measurements and the DEGAS and DEGAS 2 neutral Monte-Carlo codes to study the 3D neutral particle density, radial particle flux, and impacts of various fueling scenios in HSX.
- Gavin Weir
- Area - design, construction and implementation of the second ECH quasi-optical power transmission system for delivering power from the second 28 GHz gyrotron to HSX. The mirror is to be manually steerable to permit off-axis power deposition control.
- Carson Cook
- Carson is working on the SIESTA (Spectral Iterative Equilibrium Solver for Toroidal Applications) code development project with Steve Hirshman and Raul Sanchez of ORNL. SIESTA is a magnetohydrodynamic equilibrium code used for modeling toroidal plasmas in 3D systems. Unlike VMEC, SIESTA does not assume nested magnetic flux surfaces, so equilibria involving magnetic islands and stochastic regions can be computed. The code is very scalable, a necessary feature for ITER-relevant calculations. SIESTA will be extremely useful for equilibrium analysis in perturbed tokamaks and stellarator modeling and design.
- Bob Wilcox
- Area - plasma turbulence and flows, fluctuation induced transport,using multiple instances of multi-tipped edge-probes.
Graduated Students
- John Canik
- John studied the effects of quasisymmetry on particle
and heat transport in HSX. He did this by measuring the plasma
density and temperature profiles using a Thomson scattering
system. He also performed extensive three-dimensional
modeling of the neutral gas in HSX plasma, which has yielded the
particle source rate and neutral density.
John received his Ph.D. in Spring of 2007 and currently works at Oak Ridge National Laboratory under a prestigious Wigner Fellowship.
- Walter Guttenfelder
- Area - examining fluctuations and anomalous transport in HSX especially through 3-D modeling.
- Walter received his PhD in the Winter of 2007, and currently works at the Princeton Plasma Physics Lab in Princeton, NJ
- Jeremy Lore
- Jeremy's focus area, during his time at HSX, was stellarator transport, specifically the measurement and modeling of transport at HSX. Jeremy currently developed the PENTA code with Don Spong from ORNL, which calculates neoclassical transport quantities in stellarators or tokamaks while conserving parallel momentum. Neoclassical calculations predict a large "electron root" radial electric field (Er) in the core of HSX plasmas, with strong radial shear. The neoclassical simulations, coupled with turbulent transport calculations performed by Walter Guttenfelder have been successful in simulating the strongly peaked electron temperature profiles measured during ECR heating. The predicted electric fields and in-surface flows will be compared to ChERS measurements in the near future.
- In 2006 Jeremy implemented a displacement sensor system on HSX and performed structural modeling and testing to ensure safe operation at B=1T. Jeremy also performed analysis of data from the Thomson scattering diagnostic.
- Jeremy received his PhD in the Spring of 2010, and currently works at the Oak Ridge National Lab
- John Schmitt
- John worked on the design, installation, and analysis of the magnetic diagnostics on the HSX stellarator in order to measure the the equilibrium plasma currents present during the plasma discharge. The pressure-driven Pfirsch-Schluter current is helical in nature because of lack of toroidal curvature in the QHS magnetic spectrum, and reduced by the high effective transform (3). The net toroidal current is predominantly bootstrap-driven. The bootstrap current is modeled by PENTA, and the time and spatial evolution is modeled by a diffusion equation that includes the 3-D nature of the plasma column.
- John received his PhD in 2011 and currently works at the Princeton Plasma Physics Laboratory in Princeton, NJ.