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Introductory Course in Plasma Physics
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Overview

The National Undergraduate Fellowship Program in Plasma Physics and Fusion Energy Sciences provides outstanding undergraduates with an opportunity to conduct research in the disciplines that comprise the plasma sciences in general and fusion research in particular.

Only students who are matriculated at a U.S. college or university AND are a U.S. citizen or Permanent Resident Alien are eligible for a Fellowship.

The program is intended primarily for students completing their junior year majoring in physics or engineering, but highly motivated students completing their sophomore year are encouraged to apply as well. The nine-week long research projects are performed at one of the many participating universities and national laboratories throughout the country. The goal of the program is to stimulate students' interest in the fields relevant to fusion research while providing capable assistants for fusion research projects. In order that the students obtain a sufficient background to begin their research projects, the nine week project is preceded by a one week introductory course at the Princeton Plasma Physics Laboratory in the basic elements of plasma physics, after which the students travel to the sites of their research projects.

The Program is funded by the U.S. Department of Energy, Office of Fusion Energy Sciences.

Research Abstracts of 2009

Magnetic Transport Barriers in the DIII-D Tokamak* J. Kessler, SE Missouri State U; F. Volpe, U. Wisc.; T.E. Evans, GA; H. Ali, A. Punjabi, Hampton U

Large overlapping magnetic islands generate chaotic fields. However, a previous work [1] showed that second or third order perturbations of special topology and strength can also generate magnetic diffusion “barriers” in the middle of stochastic regions. In the present study, we numerically assess their experimental feasibility at DIII-D. For this, realistic I- and C-coils perturbations are superimposed on the equilibrium field and puncture plots are generated with a field-line tracer. A criterion is defined for the automatic recognition of barriers and successfully tested on earlier symplectic maps in magnetic coordinates. The criterion is systematically applied to the new puncture plots in search for dependencies, e.g. upon the edge safety factor q95, which might be relevant to edge localized mode (ELM) stability, as well as to assess the robustness of barriers against fluctuations of the plasma parameters and coil currents. [1] H. Ali and A. Punjabi, 2007 Plasma Phys. Control. Fusion 49 1565. *Work supported in part by the US DOE under a National Undergraduate Fusion Fellowship and DE-FC02-04ER54698.

Research Abstracts of 2008

Using Pickup Coils to Detect Magnetorotational Instability in Liquid Gallium D. COSTER, Wheaton College, M.D. NORNBERG, E. SCHARTMEN, H. JI, and A. ROACH, PPPL

The physics of accretion disks in space around bodies like black holes and forming stars is still not fully understood, particularly relating to the mechanisms of fast angular momentum transport. It has become widely accepted that the magnetorotational instability (MRI) is responsible for inciting the turbulent outward flux of angular momentum needed for fast accretion to occur. The goal of the MRI experiment is to provide a better understanding of these mechanisms by realizing MRI at a much smaller scale. It should be able to reproduce the MRI in the lab by passing a magnetic field through liquid gallium that is being quickly rotated and confined between two independently turning cylinders. Previously, non axisymmetric modes have been observed. In order to better resolve these modes, we have constructed a horizontal array of pickup coils to detect fluctuations in the magnetic field. These measurements give us information about the instabilities created in the gallium and will hopefully provide evidence for MRI. Design, calibration, and experimental results will be presented.

Measurement of the Electromagnetic Torque on a Rotating Plasma for DIII-D N. LOGAN, Brown University, E.J. STRAIT, General Atomics, H. REIMERDES, Columbia University

We study the torque of static and rotating magnetic perturbations on a rotating plasma by deriving an estimate of the electromagnetic torque from measurements of various components of the magnetic perturbation at the wall [1]. This estimate of the torque is then used to determine whether it can account for the experimentally observed changes in the plasma rotation. Preliminary analysis of the locking of a large tearing mode shows that the measured electromagnetic torques behave according to theoretical predictions of their dependency on the magnitude of magnetic perturbations and rotational frequency [2]. The observed torque varies inversely with frequency and linearly with the square of the magnitude of the perturbation. The ultimate goal is to compare the measured electromagnetic torque against the equation of motion and theoretical predictions for the braking e on a rotating plasma. [1] I.H. Hutchinson, Plasma Phys. Control. Fusion 43, 145 (2001). [2] Nave and Wesson, Nucl. Fusion 30, 2575 (1990).

The Impact of Correlations on MHD Equilibrium Reconstruction A.M. JACOBS, Hendrix College, J.M. FINN, LANL, L.L. LAO, E.J. STRAIT, GA

Equilibrium reconstruction is vital to tokamak operation and post-discharge analysis. EFIT performs equilibrium reconstruction with a c2 minimization scheme that utilizes SVD and weighs terms by the variance of the data. It is shown how this regression can be further generalized by incorporating the covariance matrix of the data, which includes correlations between measurements. Sample covariance matrices are computed and used to calculate correlations in a variety of DIII-D magnetic data. The ultimate goal is a modified version of EFIT that takes advantage of the more generalized regression scheme to explore the possibility that highly correlated data could allow for a reduction in uncertainty1. The reconstructions of traditional SVD and the generalized covariance scheme are compared. Preliminary results indicate instances of high correlation in quiescent H-mode shots. 1 “MHD Equilibrium Reconstruction in the Presence of Correlated Data” C. S. Jones et al 2006 Nucl. Fusion 46 335-349

Time-Dependent Modeling of Fast Wave Absorption with Multiple Damping Mechanisms W. UNGLAUB, Colorado School of Mines, R.I. PINSKER, General Atomics, R.W. HARVEY, CompX

Plasma response to absorption of Fast Wave (FW) power is studied in a time-dependent model in the presence of multiple damping mechanisms, including direct electron absorption and ion cyclotron harmonic damping in the core and an unspecified edge loss mechanism. Previous work on the plasma response to a step in FW power in a slab model [1] is extended to take into account additional effects such as the density rise with FW injection and confinement degradation with increased heating power. To extend this work to an axisymmetric toroidal equilibrium, we couple the GENRAY ray-tracing code to the ONETWO transport code. In both models, it is found that the final partitioning of power among the various damping mechanisms and the time needed to reach the final state strongly depend on initial conditions. The time required to reach the steady-state can be many energy confinement times. [1] R.I. Pinsker, in RF Power in Plasmas (Proc. 17th Top. Conf, 2007), (AIP, NY, 2007) p. 447.

Study of effects of external drive on MRX reconnection J. SCHROEDER, Wheaton College, M. YAMADA, PPPL

The Magnetic Reconnection Experiment (MRX) studies driven reconnection utilizing two toroidal flux cores [1]. One active topic of research is the relationship between global plasma parameters and local reconnection physics. External drive is determined by the rate at which poloidal magnetic field is pulled back into the flux cores. Findings from the TS-3 experiment [2] and recent 2-D simulations [3] have shown a linear scaling between driving parameters and reconnection rate. This study investigates the relationship of external drive to the out-of-plane electric field and the MHD inflow velocity in MRX. Initial results show a linear scaling between external drive and out-of-place electric field at low fill pressure and reduced dependence at higher fill pressure. Further analysis of the effect of external drive on other relevant plasma parameters and comparisons to 2-D kinetic simulations will be reported. [1] M. Yamada, et al., Phys. Plasmas 4(5),1936 (1997). [2] M. Yamada, et al., Physical Review Letters 65(6),721 (1990). [3] S. Dorfman, et al., Submitted to Phys. Plasmas. This work was supported by DOE, NASA, and NSF.

Stipend

Students will receive a stipend of $4,800 in addition to transportation to and from their university or permanent U.S. address. Housing for the summer, and some meals during the one-week course at Princeton will be paid by the program. Students will be responsible for their  meal expenses during the remaining nine weeks.

Applications

Applications for the 2010 Program, which runs from June 7, 2010 to August 13, 2010, are invited from students in engineering, mathematics, computer science, or physics, who are matriculated at a U.S. college or university. Students should have taken at least one course in electricity and magnetism beyond introductory physics. Deadline for application material is February 12, 2010. The application must be completed on-line.

• Official transcripts must be mailed to: NUF, PPPL, PO Box 451, Princeton, NJ 08543

On-Line Application

For additional information, please email James Morgan at jmorgan@pppl.gov.