A5041990239- Magnetic confinement fusion research
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Nuclear physics research studies
- Ionosphere and magnetosphere dynamics
- Physics of Superconductivity and Magnetism
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Astronomical and nuclear sciences
- X-ray Spectroscopy and Fluorescence Analysis
- Terahertz technology and applications
- Superconducting and THz Device Technology
- Semiconductor Quantum Structures and Devices
- Advanced Chemical Physics Studies
- Quantum Chromodynamics and Particle Interactions
- Nuclear reactor physics and engineering
- Laser-induced spectroscopy and plasma
- Quantum and electron transport phenomena
- Electron and X-Ray Spectroscopy Techniques
- Spectroscopy and Laser Applications
- Magnetic properties of thin films
- Atomic and Subatomic Physics Research
University of Tübingen
2015-2024
National Institute of Advanced Industrial Science and Technology
2015
National Institute for Materials Science
2015
Nanjing University
2015
Princeton Plasma Physics Laboratory
1988-1998
Princeton University
1988-1998
Fusion Academy
1994-1996
Fusion (United States)
1994-1996
Oak Ridge National Laboratory
1976-1994
Joint European Torus
1994
The plasma-sheath equation for a collisionless plasma with arbitrary ion temperature in plane geometry is formulated. Outside the sheath, this approximated by equation, which an analytic solution electrostatic potential obtained. In addition, distribution function, wall potential, and energy particle flux into sheath are explicitly calculated. also solved numerically no approximation of Debye length. numerical results compare well analytical when length small.
Neutral-beam heating of plasmas in the Tokamak Fusion Test Reactor at low preinjection densities [${n}_{e}$(0)\ensuremath{\simeq}${10}^{19}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$] were characterized by ${T}_{e}$(0)=6.5 keV, ${T}_{i}$(0)=20 ${n}_{e}$(0)=7\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$, ${\ensuremath{\tau}}_{E}$=170 msec, ${\ensuremath{\beta}}_{\mathrm{theta}}$=2, and a d(d,n${)}^{3}$He neutron emission rate ${10}^{16}$...
Neutral-beam--heated plasmas in TFTR show evidence of substantial non-Ohmically driven toroidal current, even for balanced beam momentum input. The observations are inconsistent with calculations including only Ohmic and beam-driven currents, presently can be matched by models the neoclassical bootstrap current.
The transport effects induced by resistive ballooning modes are estimated from a theory, and found to be mainly thermal electron conduction losses. An expression for diffusivity ${\ensuremath{\chi}}_{e}$ is derived. theoretical predictions agree well with experimental values of obtained power balance the ISX-$B$ plasmas at high poloidal beta.
A variational method is developed to find approximate solutions the Grad–Shafranov equation. The surfaces of constant poloidal magnetic flux ψ(R, Z) are obtained by solving a few ordinary differential equations, which moments equation, for Fourier amplitudes inverse mapping R(ψ, ϑ) and Z(ψ, ϑ). Analytic properties moment equations considered. Specific calculations using Impurity Study Experiment (ISX-B) Engineering Test Facility (ETF)/International Tokamak Reactor (INTOR) geometries...
The elastic scattering excitation functions of the systems $^{6}\mathrm{Li}$-$^{6}\mathrm{Li}$, $^{12}\mathrm{C}$-$^{12}\mathrm{C}$, $^{14}\mathrm{N}$-$^{14}\mathrm{N}$, $^{16}\mathrm{O}$-$^{14}\mathrm{N}$, $^{16}\mathrm{O}$-$^{15}\mathrm{N}$, $^{16}\mathrm{O}$-$^{16}\mathrm{O}$, $^{16}\mathrm{O}$-$^{18}\mathrm{O}$, and $^{18}\mathrm{O}$-$^{18}\mathrm{O}$ have been subjected to comparative optical-model analyses. gross structure characteristic all these is shown arise from potential...
Supershots in TFTR often suffer a performance deterioration characterized by gradual decrease of the DD fusion neutron yield and plasma stored energy after several hundred milliseconds auxiliary heating. The correlation between this development low m (the poloidal mode number), n toroidal number) MHD modes is studied through shot-to-shot comparisons statistical data analyses. A good observed appearance strong 3/2 4/3 macroscopic modes. magnetic island structures are using Mirnov ECE...
Confinement studies on the Impurity Study Experiment (ISX-B) in beam-heated plasmas contaminated with small quantities of low-Z impurities are reported. Experimental results correlation particle and energy confinement presented. A linear relationship plasma density is observed. As increased further, this effect saturates becomes independent electron density. The experiments have been extended to higher beam power, resulting an expansion ISX-B operating space. Impurities other than neon...
A number of unusual phenomena occur in ${\mathrm{O}}^{16}$ + ${\mathrm{C}}^{12}$ induced reactions at ${E}_{\mathrm{c}.\mathrm{m}.}=19.7$ MeV. We suggest an interpretation these effects terms a molecular resonance.
Measurements of the fusion cross sections for $^{10,11}\mathrm{B}$+$^{12}\mathrm{C}$, $^{12}\mathrm{C}$+$^{13}\mathrm{C}$, $^{12}\mathrm{C}$+$^{14}\mathrm{N}$, $^{14}\mathrm{N}$+$^{14}\mathrm{N}$, and $^{14}\mathrm{N}$+$^{16}\mathrm{O}$ at sub-Coulomb-barrier energies, together with earlier results $^{12}\mathrm{C}$+$^{12}\mathrm{C}$, $^{12}\mathrm{C}$+$^{16}\mathrm{O}$, $^{16}\mathrm{O}$+$^{16}\mathrm{O}$, show that average energy dependence section can change dramatically only small...
Neutral-beam injection of up to 2.5 MW into plasmas in the ISX-B tokamak (R0 = 0.93 m, a 0.27 BT 0.9–1.5 T, Ip 70–210 kA, e 2.5–10×1013 cm−3) has created with volume-averaged beta ∼ 2.5%, peak values 9%, and root-mean-square 3.5%. Energy confinement time is observed decrease by about factor two as beam power goes from 0 MW; caused predominantly electron falling below predictions 'Alcator scaling' 3–4 at high power. An empirical relationship form fits our measurements over wide range plasma...
Differential cross sections for the elastic scattering, single excitation ($Q=\ensuremath{-}4.43$ MeV), and mutual ($Q=\ensuremath{-}8.86$ MeV) of $^{12}\mathrm{C}$ by have been measured at 14 bombarding energies in range ${E}_{\mathrm{c}.\mathrm{m}.}=35\ensuremath{-}63$ MeV. The angular distributions extend typically from 16\ifmmode^\circ\else\textdegree\fi{} to 90\ifmmode^\circ\else\textdegree\fi{} c.m. results analyzed with optical model, distorted-wave approximation, method coupled...
An optical-model analysis of $^{12}\mathrm{C}$ + elastic scattering from ${E}_{\mathrm{c}.\mathrm{m}.}=35 \mathrm{to} 63$ MeV indicates a sensitivity the cross section at large angles (${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}\ensuremath{\sim}50\ifmmode^\circ\else\textdegree\fi{}\ensuremath{-}90\ifmmode^\circ\else\textdegree\fi{}$) to region internuclear separation extending in $r\ensuremath{\sim}2$ fm. Real nuclear potentials obtained with folding model and realistic interaction fit...
Recent operation of the Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Research 1, 51 (1986)] has produced plasma equilibria with values Λ≡βp eq+li/2 as large 7, εβp dia≡2μ0ε〈p⊥〉/〈〈Bp〉〉2 1.6, and Troyon normalized diamagnetic beta 26, 209 (1984); Lett. 110A, 29 (1985)], βNdia≡108〈βt⊥〉aB0/Ip 4.7. When dia≳1.25, a separatrix entered vacuum chamber, producing naturally diverted discharge that was sustained for many energy confinement times, τE. The largest stored were...
Local particle and heat transport coefficients have been measured in a temperature scan of neutral-beam--heated plasmas with n, ${\mathit{I}}_{\mathit{p}}$, ${\mathit{B}}_{\mathit{c}\mathit{p}\mathit{h}\mathit{i}}$ held constant. The electron is ascertained from flux analysis small density perturbation, the obtained equilibrium power balance. vary as ${\mathit{T}}_{\mathit{e}}^{\mathrm{\ensuremath{\alpha}}}$, where \ensuremath{\alpha}=1.5--2.5. observed dependence predicted by numerical...
A review of TFTR plasma transport studies is presented. Parallel and the confinement suprathermal ions are found to be relatively well described by theory. Cross-field thermal plasma, however, anomalous with momentum diffusivity being comparable ion larger than electron in neutral beam heated discharges. Perturbative experiments have studied nonlinear dependencies coefficients examined role possible nonlocal phenomena. The underlying turbulence has been using microwave scattering, emission...
Circular-limiter H modes are obtained on the TFTR tokamak during high-power neutral-beam heating. The transition is usually from supershot to mode rather than usual L transition, and thus in a low-recycling environment with core fueling mainly heating beams. As result, density pressure profiles highly peaked at center. global confinement time ${\mathrm{\ensuremath{\tau}}}_{\mathit{E}}$ enhanced over L-mode scaling by up \ensuremath{\approxeq}2.5 times. onset of edge-localized MHD shortly...
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...
Developing a tunable source of high-power terahertz radiation is an ongoing research challenge, with promise for applications including biosensing and high-speed communication. The authors show that the THz emission from stack intrinsic Josephson junctions in cuprate superconductor embedded between two gold layers can be manipulated by focused laser beam. output power increased as much 75% irradiation, tuned continuously rapidly beam moved along length stack, locally heating different spots sample.
Sources of terahertz radiation (between the far infrared and microwave frequencies) are in high demand for a host applications. The authors report on what is essentially ``T-ray flashlight'', compact portable source tunable, continuous light, employing stack intrinsic Josephson junctions cuprate superconductor as emitter. This economical convenient device can be driven by one everyday 1.5-V battery, should facilitate airport security, nondestructive evaluation, remote detection trace gases,...
The confinement and heating of supershot plasmas are significantly enhanced with tritium beam injection relative to deuterium in the Tokamak Fusion Test Reactor [Plasma Phys. Controlled 26, 11 (1984)]. global energy local thermal transport analyzed for fueled quantify their dependence on average mass hydrogenic ions. Radial profiles densities determined from D–T fusion neutron emission profile. inferred scalings isotopic quite strong, τE∝〈A〉0.85±0.20, τEthermal∝〈A〉0.89±0.20,...