D. Mueller
A5028943363- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Mass Spectrometry Techniques and Applications
- Laser-Plasma Interactions and Diagnostics
- Muon and positron interactions and applications
- Aerogels and thermal insulation
- Advanced Chemical Physics Studies
- Solar and Space Plasma Dynamics
- Copper Interconnects and Reliability
- Silicone and Siloxane Chemistry
- Nuclear reactor physics and engineering
- Nuclear Physics and Applications
- Ion-surface interactions and analysis
- Laser-induced spectroscopy and plasma
- Particle Accelerators and Free-Electron Lasers
- Analytical chemistry methods development
- Electron and X-Ray Spectroscopy Techniques
- Radiation Therapy and Dosimetry
- Atomic and Subatomic Physics Research
Princeton Plasma Physics Laboratory
2010-2023
General Atomics (United States)
1997-2020
Princeton University
2001-2019
University of North Texas
1993-2011
Australian National University
2009-2011
University of Washington
2003-2007
Oak Ridge National Laboratory
1988-2007
University of Baltimore
2006-2007
Johns Hopkins University
2003-2007
Columbia University
2003-2007
Strong magnetohydrodynamic activity has been observed in PDX neutral-beam-heated discharges. It occurs for ${\ensuremath{\beta}}_{T}q>~0.045$ and is associated with a significant loss of fast ions drop neutron emission. As much as 20%-40% the beam heating power may be lost. The instability repetitive bursts oscillations \ensuremath{\le} 1 msec duration at 1-6-msec intervals. dubbed "fishbone instability" from its characteristic signature on Mirnov coils.
Deuterium neutral beams with energies up to 110 keV were injected into TFTR (Tokamak Fusion Test Reactor) plasmas at low magnetic field such that the beam injection velocities comparable Alfv\'en velocity. Excitation of toroidal eigenmodes was observed by Mirnov coils and emission spectroscopy.
The National Spherical Torus Experiment (NSTX) is being built at Princeton Plasma Physics Laboratory to test the fusion physics principles for spherical torus concept MA level. NSTX nominal plasma parameters are R0 = 85 cm, a 67 R/a ⩾ 1.26, Bt 3 kG, Ip 1 MA, q95 14, elongation κ ⩽ 2.2, triangularity δ 0.5 and pulse length of up 5 s. heating/current drive tools high harmonic fast wave (6 MW, s), neutral beam injection (5 80 keV, s) coaxial helicity injection. Theoretical calculations predict...
Abstract The spherical tokamak (ST) is a leading candidate for Fusion Nuclear Science Facility (FNSF) due to its compact size and modular configuration. National Spherical Torus eXperiment (NSTX) MA-class ST facility in the US actively developing physics basis an ST-based FNSF. In plasma transport research, experiments exhibit strong (nearly inverse) scaling of normalized confinement with collisionality, if this trend holds at low high fusion neutron fluences could be achievable very...
Dielectronic recombination has been directly observed with use of crossed beams electrons and ${\mathrm{Mg}}^{+}$ ions. Measurements were made delayed coincidences between the stabilizing photon near 280 nm resultant neutral atom, cross sections determined. Theoretical are more than a factor 5 smaller those measured.
National Spherical Torus Experiment [which M. Ono et al., Nucl. Fusion 40, 557 (2000)] high-power divertor plasma experiments have shown, for the first time, that benefits from lithium coatings applied to facing components found previously in limited plasmas can occur also diverted configurations. Lithium were with pellets injected into helium discharges, and an oven directed a collimated stream of vapor toward graphite tiles lower center stack divertor. depositions few milligrams 1g been...
Abstract Ion temperatures of over 100 million degrees Kelvin (8.6 keV) have been produced in the ST40 compact high-field spherical tokamak (ST). excess 5 keV not previously reached any ST and only obtained much larger devices with substantially more plasma heating power. The corresponding fusion triple product is calculated to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>n</mml:mi> <mml:mi>i</mml:mi> <mml:mn>0</mml:mn>...
Research in NSTX has been conducted to establish spherical torus plasmas be used for high β, auxiliary heated experiments. This device a major radius R0 = 0.86 m and midplane halfwidth of 0.7 m. It operated with toroidal magnetic field B0 ⩽ 0.3 T Ip 1.0 MA. The evolution the plasma equilibrium is analysed between discharges an automated version EFIT code. Limiter, double null lower single diverted configurations have sustained several energy confinement times. stored reached 92 kJ (βt 17.8%)...
The National Spherical Torus Experiment (NSTX) has demonstrated the advantages of low aspect ratio geometry in accessing high toroidal and normalized plasma beta, βN ≡ 108⟨βt⟩ aB0/Ip. Experiments have reached βt = 39% 7.2 through boundary profile optimization. High plasmas can exceed ideal no-wall stability limit, βNno−wall, for periods much greater than wall eddy current decay time. Resistive mode (RWM) physics is studied to understand stabilization these plasmas. spectrum unstable RWMs...
Peak fusion power production of 6.2\ifmmode\pm\else\textpm\fi{}0.4 MW has been achieved in TFTR plasmas heated by deuterium and tritium neutral beams at a total 29.5 MW. These have an inferred central alpha particle density 1.2\ifmmode\times\else\texttimes\fi{}${10}^{17}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$ without the appearance either disruptive magnetohydrodynamics events or detectable changes Alfv\'en wave activity. The measured loss rate energetic particles agreed with...
The NSTX operates at low aspect ratio (R/a ∼ 1.3) and high beta (up to 40%), allowing tests of global confinement local transport properties that have been established from higher devices. plasmas are heated by up 7 MW deuterium neutral beams with preferential electron heating as expected for ITER. Confinement scaling studies indicate a strong BT dependence, current dependence is weaker than observed ratio. Dimensionless experiments increase in decreasing collisionality weak degradation...
The effects of state mixing by extrinsic fields in the collision region have been investigated for dielectronic recombination process ${\mathrm{Mg}}^{+}$(3s)+e\ensuremath{\rightarrow}Mg(3p,nl)\ensuremath{\rightarrow}Mg(3s ,nl)+h\ensuremath{\nu}. By field ionization Rydberg atoms produced, cross sections \ensuremath{\sigma}(${n}_{f}$) measured. observed large changes with alteration provide first incontrovertible experimental evidence that can be changed external fields.
Measurements of total scattering by positron impact have typically excluded a significant portion the forward angles differential cross section. This paper demonstrates effect that this can on measurements We show much apparent disagreement between experimental from atoms and molecules may be explained angular range. It is shown same also lead to an anomalous energy dependence some sections.
Abstract ST40 is a compact, high-field ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mi mathvariant="normal">T</mml:mi> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mtext>⩽</mml:mtext> <mml:mn>2.1</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mtext>T</mml:mtext> </mml:math> ) spherical tokamak (ST) with mission to expand the physics and technology basis for ST route commercial fusion. The research programme covers...
Dedicated experiments in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion, 42, 614 (2002)], Joint European Torus (JET) [P. H. Rebut, R. J. Bickerton, and B. E. Keen, Fusion 25, 1011 (1985)], National Spherical Experiment (NSTX) [M. Ono, S. M. Kaye, Y.-K. Peng et al., 40, 557 (2000)] reveal commonalities of resistive wall mode (RWM) stabilization by sufficiently fast toroidal plasma rotation devices different size aspect ratio. In each device weakly damped n=1 RWM manifests itself resonant field...
Global magnetohydrodynamic (MHD) stability limits in the National Spherical Torus Experiment (NSTX) have increased significantly recently due to a combination of device and operational improvements. First, more routine H-mode operation with broadened pressure profiles allows access higher normalized β lower internal inductance. Second, correction poloidal field coil induced error-field has largely eliminated locked tearing modes during normal maximum achievable β. As result these...
Experimental details are presented for the measurement of effects extrinsic electric fields on cross sections and Rydberg product-state distributions dielectronic recombination ${\mathrm{Mg}}^{+}$ with electrons. A new type state detector is described. results in presence three field values, these compared theoretical calculations.
Dedicated $H$-mode parameter scans in the high-power National Spherical Torus Experiment have been used to establish confinement scaling and underlying transport trends at low aspect ratio ($R/a\ensuremath{\simeq}1.3$). These indicate a strong dependence of global thermal energy times on toroidal field, ${B}_{T}^{0.9}$, while their plasma current is weaker, ${I}_{p}^{0.4}$. Local analysis indicates that electrons control ${B}_{T}$ scaling, whereas ions ${I}_{p}$ with...
Strong minority proton heating is produced in the Princeton Large Torus through ioncyclotron resonance damping of fast waves at moderate rf power levels. In addition to demonstrating good confinement, energy distribution consistent with Fokker-Planck theory which provides prescription for extrapolation this regime higher levels and other species.
New measurements for the total, single ionization of ${\mathrm{B}}^{2+}$ and ${\mathrm{O}}^{5+}$ by electron impact are reported with particular attention directed to indirect contribution excitation-autoionization. For these first our knowledge while present data improve on previous measurements. In both cases direct total cross sections in good agreement recent distorted-wave predictions Younger, excitation-autoionization is consistent other Li-like ions. an additional small increase...
Results from experiments on DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high-qmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 MW of heating power applied the intent maximizing βN and noninductive However, in qmin&gt;2 target typical range q95= 5–7 used next-step reactor models, Alfvén eigenmodes...