D. A. Rasmussen
A5064672012- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Gyrotron and Vacuum Electronics Research
- Laser-Plasma Interactions and Diagnostics
- Microwave Engineering and Waveguides
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Nuclear reactor physics and engineering
- Antenna Design and Analysis
- Laser-induced spectroscopy and plasma
- Digital Holography and Microscopy
- Electromagnetic Launch and Propulsion Technology
- Particle Accelerators and Free-Electron Lasers
- HVDC Systems and Fault Protection
- Atomic and Subatomic Physics Research
- Underwater Vehicles and Communication Systems
- Semiconductor materials and devices
- Dust and Plasma Wave Phenomena
- Electromagnetic Simulation and Numerical Methods
- Semiconductor Lasers and Optical Devices
- Radio Frequency Integrated Circuit Design
Oak Ridge National Laboratory
2012-2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2013
CEA Cadarache
2013
Integrated Test Range
2011
ITER
2011
Princeton Plasma Physics Laboratory
1986-2009
General Atomics (United States)
2006-2009
Boeing (Australia)
2007
Tech-X Corporation (United States)
2007
University of Illinois Urbana-Champaign
2007
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...
A 20 MW/5 GHz lower hybrid current drive (LHCD) system was initially due to be commissioned and used for the second mission of ITER, i.e. Q = 5 steady state target. Though not part currently planned procurement phase, it is now under consideration an earlier delivery. In this paper, both physics technology conceptual designs are reviewed. Furthermore, appropriate work plan also developed. This design, R&D, installation a MW LHCD on ITER follows Scientific Technical Advisory Committee...
Pellet injection from the inner wall is planned for use in ITER as primary core fuelling system since gas expected to be highly inefficient burning plasmas. Tests of guide tube have shown that 5 mm pellets with up 300 m s−1 speeds can survive intact and provide necessary rate. Modelling extrapolation pellet experiments present day's smaller tokamaks leads prediction this method will efficient beyond pedestal region. Using triggering frequent small edge localized modes an attractive...
A linearly polarized (LP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mn</sub> ) mode basis set for oversized, corrugated, metallic waveguides is derived the special case of quarter-wavelength-depth circumferential corrugations. The relationship between LP modes and conventional (HE , EH TE xmlns:xlink="http://www.w3.org/1999/xlink">0n</sub> TM corrugated guide shown. loss in a gap or equivalent miter bend waveguide calculated single-mode...
Plasma fuelling with pellet injection, pacing of edge localized modes (ELMs) by small frequent pellets and disruption mitigation gas jets or injected solid material are some the most important technological capabilities needed for successful operation ITER. Tools being developed at Oak Ridge National Laboratory that can be employed on ITER to provide necessary core ELMs disruptions. Here we present progress development technology reliable high throughput inner wall fuelling, ELM frequency...
A disruption mitigation system (DMS) is under design for ITER to inject sufficient material deeply into the plasma rapid thermal shutdown and collisional suppression of any resulting runaway electrons. Progress on development both a shattered pellet injector (SPI) that produces large solid cryogenic pellets provide reliable deep penetration fast opening high flow rate gas valve massive injection (MGI) presented. Cryogenic deuterium neon up 25 mm in size have been formed accelerated with...
The Tomamak Fusion Test reactor has performed initial high-power experiments with the plasma fueled nominally equal densities of deuterium and tritium. Compared to pure plasmas, energy stored in electron ions increased by \ensuremath{\sim}20%. These increases indicate improvements confinement associated use tritium possibly heating electrons \ensuremath{\alpha} particles created D-T fusion reactions.
The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high βT in order advance spherical torus (ST) concept. In do this, NSTX utilizes up 7.5 MW neutral beam injection, 6 harmonic fast waves (HHFWs), it operates with plasma currents 1.5 MA elongations 2.6 a field 0.45 T. New facility, diagnostic modelling capabilities developed over past two years have enabled research team make significant progress...
The TFTR tokamak has reached its original machine design specifications (Ip=2.5 MA and BT=5.2 T). Recently, the D degrees neutral beam heating power been increased to 6.3 MW. By operating at low plasma current (Ip approximately=0.8 MA) density (ne approximately=1*1019 m-3), high ion temperatures (9+or-2 keV) rotation speeds (7*105 m/s) have achieved during injection. At opposite extreme, pellet injection into plasmas used increase line-average 8*1019 m-3 central 1.6*1020 m-3. This wide range...
Access to the MHD second stability regime has been achieved in ATF torsatron. Experimental \ensuremath{\beta} values (${\ensuremath{\beta}}_{0}$\ensuremath{\le}3%, with fast ions contributing \ensuremath{\approxeq}(1/3 of pressure at high \ensuremath{\beta}) are well above theoretical transition value (${\ensuremath{\beta}}_{c}$\ensuremath{\approxeq}1.3% for ideal modes) required reach this regime. The relatively low ${\ensuremath{\beta}}_{c}$ results from operation peaked profiles. measured...
The ITER electron cyclotron heating (ECH) transmission lines (TLs) are 63.5-mm-diam corrugated waveguides that will each carry 1 MW of power at 170 GHz. TL is defined here as the waveguide system connecting gyrotron mirror optics unit (MOU) to entrance ECH launcher and includes miter bends other components. losses on have been calculated for four possible cases corresponding having HE11 mode purity input 100, 97, 90, 80%. due coupling, ohmic, conversion loss evaluated in detail using a...
AbstractThe use of a fusion component testing facility to study and establish, during the ITER era, remaining scientific technical knowledge needed by Demo is considered described in this paper. This aims test components an integrated nuclear environment, for first time, discover understand underpinning physical properties, develop improved further testing, time-efficient manner. It requires design with extensive modularization remote handling activated components, flexible hot-cell...
Injection of massive quantities noble gases or D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has proven to be effective at mitigating some the deleterious effects disruptions in tokamaks. Two alternative methods that might offer advantages over present technique for gas injection are ¿shattering¿ pellets and employing close-coupled rupture disks. Laboratory testing been carried out evaluate their feasibility. For study pellets, a...
The transmission line (TL) subsystem associated with the ITER electron cyclotron heating and current drive system has reached conceptual design maturity. At this stage responsibility of finalizing been transferred from Organization to U.S. Domestic Agency. purpose TL is transmit microwaves generated by 170-GHz gyrotrons installed in radio-frequency building launchers located one equatorial four upper tokamak ports. Each consists evacuated HE11 waveguides, direct-current breaks, power...
Shattered pellet injection (SPI) has been selected as the baseline technology for disruption mitigation (DM) system ITER. Typical SPI utilizes cryogenic cooling to desublimate low pressure (<100 mbar) gases onto a cold zone within pipe gun barrel, forming cylindrical pellet. Pellets are dislodged from barrel and accelerated using either gas driven mechanical punch or high-pressure light-gas delivered by fast-opening valve. developed at Oak Ridge National Laboratory is currently deployed...
The toroidal current observed during electron cyclotron heating in the Advanced Toroidal Facility torsatron is identified as bootstrap current. currents, ranging between +4 and -2 kA, agree well with predictions of neoclassical theory magnitude parametric dependence, determined by systematic scans quadrupole (shaping) dipole (magnetic axis shift) moments poloidal magnetic field. It has been shown that a stellarator can be externally controlled, zero-current operation achieved.
The National Spherical Torus Experiment (NSTX) has made considerable progress in advancing the scientific understanding of high performance long-pulse plasmas needed for future spherical torus (ST) devices and ITER.Plasma durations up to 1.6 s (five current redistribution times) have been achieved at plasma currents 0.7 MA with non-inductive fractions above 65% while simultaneously achieving β T N values 17% 5.7 (%m -1 ), respectively.A newly available motional Stark effect diagnostic...
A two-frequency correlation reflectometer has been operated on the Advanced Toroidal Facility (ATF) to measure plasma electron density fluctuations. This uses quadrature phase detection permit true measurement of reflected microwave signal (probing beam). By measuring fluctuations in probing beam, amplitude can be estimated. Simultaneous operation makes it possible coherence between at two radially separated cut-off layers, from which radial lengths and wavenumbers used study edge gradient...
The National Spherical Torus Experiment (NSTX) has explored the effects of shaping on plasma performance as determined by many diverse topics including stability global magnetohydrodynamic (MHD) modes (e.g., ideal external kinks and resistive wall modes), edge localized (ELMs), bootstrap current drive, divertor flux expansion, heat transport. Improved capability been crucial to achieving βt∼40%. Precise shape control achieved NSTX using real-time equilibrium reconstruction. simultaneously...
A twin-screw extruder for the ITER pellet injection system is under development at Oak Ridge National Laboratory. The will provide a stream of solid hydrogen isotopes to secondary section, where pellets are cut and accelerated with single-stage gas gun into plasma. one-fifth scale prototype has been built produce continuous deuterium extrusion.Deuterium precooled liquefied before being introduced extruder. precooler consists copper vessel containing liquid nitrogen surrounded by filled coil....
The three dimensional (3-D) nature of antennas for fusion applications in the ion cyclotron range frequencies (ICRF) requires accurate modelling to design and analyse new antennas. In this article, analysis tools radiofrequency (RF) are successfully benchmarked with experiment, 3-D physics launched waves is explored. systematic combines measured density profiles from a reflectometer system, transmission line circuit modelling, detailed magnetostatics electromagnetic antenna model including...