Showing papers by "Princeton Plasma Physics Laboratory published in 1992"
TL;DR: A nonvariational kinetic-MHD stability code (NOVA-K) was developed to integrate non-Hermitian integro-differential eigenmode equations due to energetic particles in a general flux coordinate (ψ, θ, ζ) system with an arbitrary Jacobian.
228 citations
TL;DR: Lower hybrid waves are a demonstrated, continuous means of driving toroidal current in a tokamak, and waves traveling in one poloidal direction, in addition to being directed in one toroidal direction are shown to be the most efficient drivers of current in the presence of the energetic {alpha}-particles.
Abstract: Lower hybrid waves are a demonstrated, continuous means of driving toroidal current in a tokamak. When these waves propagate in a tokamak fusion reactor, in which there are energetic {alpha}- particles, there are conditions under which the {alpha}-particles do not appreciably damp, and may even amplify, the wave, thereby enhancing the current-drive effect. Waves traveling in one poloidal direction, in addition to being directed in one toroidal direction, are shown to be the most efficient drivers of current in the presence of the energetic {alpha}-particles.
222 citations
TL;DR: Results are presented that demonstrate the proof of principle of a soft-x-ray reflection imaging microscope in the Schwarzschild configuration using Mo/Si multilayer mirrors with a normal-incidence reflectivity of ~20% per surface at 18.2 nm.
Abstract: We present results that demonstrate the proof of principle of a soft-x-ray reflection imaging microscope in the Schwarzschild configuration. A soft-x-ray laser operating at 18.2 nm was used as the x-ray source. Mo/Si multilayer mirrors with a normal-incidence reflectivity of ~20% per surface at 18.2-nm wavelength were used in the Schwarzschild objective.
42 citations
TL;DR: The ARIES research program is a multi-institutional effort to develop several visions of tokamak reactors with enhanced economic, safety, and environmental features as mentioned in this paper, and four ARIES visions are currentl...
Abstract: The ARIES research program is a multi-institutional effort to develop several visions of tokamak reactors with enhanced economic, safety, and environmental features. Four ARIES visions are currentl...
31 citations
TL;DR: In this paper, the poloidal and toroidal spatial distributions of D α, He I and C II emission have been obtained in the vicinity of the TFTR bumper limiter and are compared with models of ion flow to the surface.
25 citations
TL;DR: In this paper, it was speculated that the carbon influx during a carbon bloom results in a limiter surface which has a slightly reduced self-sputtering yield for the subsequent discharge.
22 citations
TL;DR: Palladium and LaNi5-xAlx (x=0.30, 0.75,0.85), which form reversible hydrides, are used for tritium processing and storage in the Savannah River Site (SRS) TRITium facilities as discussed by the authors.
Abstract: Palladium and LaNi5-xAlx (x=0.30, 0.75, 0.85), which form reversible hydrides, are used for tritium processing and storage in the Savannah River Site (SRS) tritium facilities. As part of a program ...
20 citations
TL;DR: In this paper, the operating experiences obtained with a set of scintillator-based escaping fast ion detectors which have been used successfully for several years on the TFTR tokamak were reviewed.
Abstract: This paper reviews the operating experiences obtained with a set of scintillator‐based escaping fast ion detectors which have been used successfully for several years on the TFTR tokamak. There have been several operational problems which need to be resolved before these detectors are used to measure 3.5 MeV DT alphas in 1993. The main problem has been overheating by edge plasma heat flux for large major radius plasmas, when the detectors were not shadowed by the adjacent limiter. Other problems have been due to runaway electron‐induced x‐ray flux and scintillator and foil damage.
14 citations
TL;DR: In this paper, the effects of atomic physics processes such as ionization, charge exchange, and radiation on the linear stability of dissipative drift waves are investigated in toroidal geometry, both numerically and analytically.
Abstract: The effects of atomic physics processes such as ionization, charge exchange, and radiation on the linear stability of dissipative drift waves are investigated in toroidal geometry, both numerically and analytically. For typical Tokamak Fusion Test Reactor (TFTR) [Plasma Physics and Controlled Nuclear Fusion Research, 1986 (IAEA, Vienna, 1987), Vol. 1, p. 51] and Texas Experimental Tokamak (TEXT) [Nucl. Technol. Fusion 1, 479 (1981)] edge parameters, overall linear stability is determined by the competition between the destabilizing influence of ionization and the stabilizing effect due to the electron temperature gradient. An analytical expression for the linear marginal stability condition, ηcrite, is derived. The instability is most likely to occur at the extreme edge of tokamaks with a significant ionization source and a steep electron density gradient.
14 citations
TL;DR: In this paper, materials used in D-T-burning fusion devices may suffer significant degradation of structural, optical, and electrical properties, either promptly upon irradiation or after accumulation of structural damage.
13 citations
TL;DR: The tritium pellet injector (TPI) for the Tokamak Fusion Test Reactor (TFTR) was designed to provide 3.3 to 4.5 mm in diameter in arbitrarily programmable firing sequences at speeds up to approximately 1.5 km/s for the three single-stage drivers and 2.5 to 3 mm for the two-stage driver.
Abstract: The tritium pellet injector (TPI) for the Tokamak Fusion Test Reactor (TFTR) will provide a tritium pellet fueling capability with pellet speeds in the 1- to 3-km/s range for the TFTR deuterium-tritium (D-T) phase. The existing TFTR deuterium pellet injector (DPI) has been modified at Oak Ridge National Laboratory (ORNL) to provide a four-shot, tritium-compatible, pipe-gun configuration with three upgraded single-stage pneumatic guns and a two-stage light gas gun driver. The TPI was designed to provide pellets ranging from 3.3 to 4.5 mm in diameter in arbitrarily programmable firing sequences at speeds up to approximately 1.5 km/s for the three single-stage drivers and 2.5 to 3 km/s for the two-stage driver. Injector operation is controlled by a programmable logic controller. The new pipe-gun injector assembly was installed in the modified DPI guard vacuum box, and modifications were made to the internals of the DPI vacuum injection line, including a new pellet diagnostics package. Assembly of these modified parts with existing DPI components was then completed, and the TPI was tested at ORNL with deuterium pellet. Results of the limited testing program at ORNL are described. The TPI is being installed on TFTR to support the D-D run period in 1992.more » In 1993, the tritium pellet injector will be retrofitted with a D-T fuel manifold and secondary tritium containment systems and integrated into TFTR tritium processing systems to provide full tritium pellet capability.« less
TL;DR: The TFTR limiter is graphite as mentioned in this paper, and it is possible to decrease the amount of D trapped in the limiter by making plasma discharges with gas injected only as a prefill.
TL;DR: In this article, the infrared emission of beam heated TFTR discharges using the high collection efficiency TFTR Thompson scattering system was studied, and it was found that emission in the vicinity of 9800 A can be used to study fluctuations in the bremsstrahlung emission.
Abstract: The infrared emission of beam heated TFTR discharges is studied using the high collection efficiency TFTR Thompson scattering system. It is found that emission in the vicinity of 9800 A can be used to study fluctuations in the bremsstrahlung emission. Low‐frequency (<40 kHz) fluctuations that are associated with MHD modes and high‐frequency (≳200 kHz) bursts of fluctuations are observed. Both coherent and incoherent fluctuations exist. In some cases, the observed coherent fluctuations can be interpreted as being due to density fluctuations as high as 5%. The rms value of broadband density turbulence in the near central regions of the plasma is estimated to be about 1%.
TL;DR: In this paper, the authors investigated the effect of disruptions on the first wall of TFTR due to an extensive array of thermocouples, and compared results from discharges with and without disruptions, extracting effects due to the disruption alone.
TL;DR: In this paper, the potential of 5 eV neutral atomic oxygen beams for dry development of photoresist is demonstrated for application in patterning of CMOS devices, which enables the use of a self-contained dry processing strategy with oxygen beam for resist etching and chlorine beam for polysilicon etching.
Abstract: Novel processing methods are being studied to address the highly selective and directional etch requirements of the ULSI manufacturing era; neutral molecular and atomic beams are two promising candidates. In this study, the potential of 5 eV neutral atomic oxygen beams for dry development of photoresist is demonstrated for application in patterning of CMOS devices. The patterning of photoresist directly on polysilicon gate layers enables the use of a self-contained dry processing strategy, with oxygen beams for resist etching and chlorine beams for polysilicon etching. Exposure to such reactive low-energy species and to the UV radiation from the line-of-sight, high-density plasma source can, however, after MOSFET gate oxide quality, impacting device performance and reliability. We have studied this processing related device integrity issue by subjecting polysilicon gas MOS structures to exposure treatments similar to those used in resist patterning using low energy oxygen beams. Electrical C-V characterization shows a significant increase in the oxide trapped charge and interface state density upon low energy exposure. I-V and dielectric breakdown characterization show increased low-field leakage characteristics for the same exposure. High-field electron injection studies reveal that the 0.25-V to 0.5-V negative flatband shifts can be partially annealed by the carrier injection. Thismore » could be due to positive charge annihilation or electron trapping, or some combination of both. Physical and analysis of patterned resist layers and electrical characterization data of MOS structures exposed to different neutral beam processing environments and following thermal annealing treatments is presented.« less
United States Naval Research Laboratory1, Oak Ridge National Laboratory2, University of Texas at Austin3, Princeton Plasma Physics Laboratory4, Lawrence Livermore National Laboratory5, Massachusetts Institute of Technology6, Columbia University7, University of Delaware8, General Atomics9, Los Alamos National Laboratory10, New York University11
TL;DR: The panel suggested that if DOE were commited to the idea of concept improvement, it needed to overcome the existing impression it was not receptive to new ideas and support the development of new concepts and ideas.
Abstract: The charge to Panel 3 was to look at the idea of concept improvements in the context of US DOE management of the magnetic fusion program. The panel suggested that if DOE were commited to the idea of concept improvement, it needed to overcome the existing impression it was not receptive to new ideas. In part the long time scale for development of fusion energy, coupled with the rate of change of scientific programs and research based on emerging knowledge, means that in general the program will be much different ten to twenty years in the future. To be able to meet this changing direction, the US program must maintain an openness to look at promising alternative ideas, spend money on developing the ideas, and consider funding some to intermediate development levels. Stellerator research was offered as one alternative to consider in light of present international work. The panel urged supporting the development of new concepts and ideas, as well as continued support for plasma physics basic research.
TL;DR: In this article, a Thomson scattering system has been designed and installed on the T −10 tokamak at the Kurchatov Institute of Atomic Energy in the US.
Abstract: As part of a US–USSR collaboration on electron cyclotron heating and current drive, a small‐angle Thomson scattering system has been designed and installed on the T‐10 tokamak at the Kurchatov Institute of Atomic Energy. The system makes use of a 20‐J Nd‐glass laser, provided by Kurchatov, that can deliver up to four pulses at energies greater than 20 J. The detection system uses an axicon‐based collection optics and high quantum efficiency avalanche photodiodes. The combination of high laser power, high quantum efficiency of the photodiodes, and the small scattering angle geometry make it possible to observe either the perpendicular or parallel (to the tokamak magnetic field) electron distribution function to energies greater than three times the electron thermal energy, at plasma densities of 1013/cm3.
TL;DR: In this paper, an empirically based scaling relation for the thermal diffusivity, sχ⊥, in the scrape-off layers (SOL) of tokamaks was generated.
TL;DR: Experiments have been performed on a linear, lower-hybrid-wave-heated plasma device in which a low-temperature, magnetized, helium plasma of collisionality ∼1-10 is produced as mentioned in this paper.