Download or read book Frequency Density and Spectrum Considerations for Lower hybrid Wave Absorption in the Tokamak de Varennes written by I. P. Shkarofsky and published by . This book was released on 1988 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of magnitude of diffusion spectrum on lower hybrid wave absorption in current drive written by I. P. Shkarofsky and published by . This book was released on 1987 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantification of Lower Hybrid Wave Absorption in the Edge of the Alcator C Mod Tokamak written by Ian Charles Faust and published by . This book was released on 2016 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: A 1 MW Lower Hybrid Current drive (LHCD) radiofrequency system is used to replace inductive drive on the Alcator C-Mod tokamak. It was designed to test Advanced Tokamak (AT) scenarios for future steady-state diverted, high field tokamaks. However, at reactor-relevant densities (n̄e > 1 . 10 20 m-3), an anomalous current drive loss is observed. This loss, known as the LHCD density limit, occurs in diverted plasmas and is correlated with the plasma current and plasma density. Several mechanisms have been implicated in the loss of current drive, with both experimental and theoretical results suggesting edge power loss. Power modulation is a standard technique used for characterizing power sources and plasma power balance. In this case, the Lower Hybrid radiofrequency (LHRF) power is modulated in time in a set of plasmas across the density range from efficient to negligible current drive. This data is used to characterize the absorption of LHRF power through the calculation of the LHRF power balance within 15%, typical of power balance studies. This power balance is used to derive characteristics of the cause behind the LHCD density limit. The immediate nature of LHRF-induced conducted and radiated power losses confirm that LHRF power is absorbed in the edge plasma, even at the lowest densities. The edge losses increase to balance the reduced current drive, indicating that the observed power in the scrape-off-layer (SOL) limits the available power for current drive and the edge losses represent a parasitic mechanism. Unlike edge losses of other radiofrequency systems, this absorption occurs with a high degree of toroidal symmetry near the plasma separatrix. This indicates absorption occurs just inside the separatrix, or just outside the separatrix over multiple SOL traversals. Measurements of the poloidal distribution of ionization and recombination in the edge were made using a specially designed Ly[alpha] pinhole camera. It utilizes a MgF2 filter and AXUV diode array to measure Ly[alpha] emission from the lower to upper divertor. Edge deposited LHRF power was found to promptly ionize the active divertor plasma in all diverted topologies. This result highlights the power flow and importance of the divertor plasma in the LHCD density limit. Three independent characteristics indicate the thermal absorption of LHRF power. First, in- /out balance of radiated and conducted LHRF power change with the reversal of the tokamak magnetic fields. Second, comparisons of the conducted heat via Langmuir probes and IR thermography are similar with and without LHRF power. Lastly, the Langmuir probe ratio of Vf l/Te does not significantly modulate with modulated LHRF. A second experiment utilized a high strike-point diverted discharge to determine the edge loss of fast electrons. The high strike point could be observed using the hard X-ray camera, which can compare core and edge X-ray emission. The measured count rates from thick-target bremsstrahlung were interpreted into fast electron fluxes using the Win X-ray code. Theoretical treatments of the fast-electron confinement time were also calculated for Alcator C-Mod. In all cases the fast-electron edge losses are minimal and will be unimportant for future tokamaks due to the small fast electron diffusivity and their large size. The loss of current drive in high density diverted plasmas correlates with high edge plasma collisionality. The newly derived characteristics set stringent requirements in nk for electron Landau damping to cause the edge absorption of LHRF power. Several observed attributes, namely high frequency modulation and low density absorption do not correlate with Landau damping characteristics. However, parasitic collisional absorption in the divertor plasma yields the necessary plasma current, topology, symmetry, thermal, and ionization characteristics. High divertor plasma collisionality is expected if not required for future tokamaks. LHRF systems of future tokamaks must must avoid propagation through collisional regions, even on the first traversal through the SOL.
Download or read book Density Regimes for Lower Hybrid Wave Coupling in Tokamak Plasmas written by and published by . This book was released on 1983 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectrum and Propagation of Lower Hybrid Waves in the Alcator C Tokamak written by R. L. Watterson and published by . This book was released on 1984 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1991 with total page 1586 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Frequency Scaling of the Lower hybrid Current Drive Density Limit in Tokamak Plasmas written by Matthew James Mayberry and published by . This book was released on 1985 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Density Regimes for Lower Hybrid Wave Carpling in Tokamak Plasma written by and published by . This book was released on 1983* with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Density Threshold for Lower Hybrid Wave Interaction with Electrons in the FT Tokamak written by European Economic Community and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectrum Broadening and Fluctuations of Lower Hybrid Waves Observed in CASTOR Tokamak written by F. Žáček and published by . This book was released on 1999 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lower hybrid Current Drive and Heating at omega p e omega c e 1 in the Tokamak de Varennes written by I. P. Shkarofsky and published by . This book was released on 1988 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation of Full wave Effects on Lower hybrid Wave Propagation Absorption and Current Drive written by Samuel Frank (Nuclear engineer) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lower hybrid current drive (LHCD) has been used as a radio-frequency (RF) heating and current drive actuator in tokamaks for over 40 years. However, despite being one of the first experimentally demonstrated sources of RF current drive, LHCD has never been consistently predicted by numerical simulation using coupled raytracing Fokker-Planck (FP) models. One frequently cited source of this discrepancy is the breakdown of the WKB approximation raytracing is based upon and "full-wave" effects such as diffraction and interference which raytracing cannot resolve. However, this claim has never been thoroughly investigated. In this work, we replace the raytracing model for wave propagation and damping in LHCD simulations with TORLH, a semi-spectral full-wave model that directly solves for the wave fields in order to assess the validity of raytracing. Using groundbreaking TORLH simulations, we demonstrate that in most modern tokamak core scenarios LHCD raytracing/FP calculations closely match full-wave/FP results. We found that previous discrepancies between raytracing and full-wave results in many cases can be attributed to improper controls and a lack of self-consistency in the full-wave/FP iteration. Our simulations of Alcator C-Mod, DIII-D, and the Experimental Advanced Superconducting Tokamak (EAST), suggest full wave effects are unlikely to be of particular importance in reactor-like scenarios where the LH wave is single pass damped, or even in modern experiments where the lower-hybrid wave is weakly damped.
Download or read book INIS Atomindex written by and published by . This book was released on 1985 with total page 1574 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Fusion Plasmas written by Olivier Sauter and published by American Institute of Physics. This book was released on 2008-12-02 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Joint Varenna-Lausanne International Workshop on Theory of Fusion Plasmas takes place every other year in a place particularly favorable for informal and in depth discussions. Invited and contributed papers present state-of-the art researches in theoretical plasma physics, covering all domains relevant to fusion plasmas. This workshop always allows a fruitful mix of experienced researchers and students, to allow for a better understanding of the key theoretical physics models and applications, such as: Theoretical issues related to burning plasmas; Anomalous Transport (Turbulence, Coherent Structures, Microinstabilities) RF Heating and Current Drive; Macroinstabilities; Plasma-Edge Physics and Divertors; Fast particles instabilities.
Download or read book The Fairy Tale of Nuclear Fusion written by L. J. Reinders and published by Springer Nature. This book was released on 2021-05-20 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: This carefully researched book presents facts and arguments showing, beyond a doubt, that nuclear fusion power will not be technically feasible in time to satisfy the world's urgent need for climate-neutral energy. The author describes the 70-year history of nuclear fusion; the vain attempts to construct an energy-generating nuclear fusion power reactor, and shows that even in the most optimistic scenario nuclear fusion, in spite of the claims of its proponents, will not be able to make a sizable contribution to the energy mix in this century, whatever the outcome of ITER. This implies that fusion power will not be a factor in combating climate change, and that the race to save the climate with carbon-free energy will have been won or lost long before the first nuclear fusion power station comes on line. Aimed at the general public as well as those whose decisions directly affect energy policy, this book will be a valuable resource for informing future debates.
Download or read book Tokamak Start Up Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor Ettor Majorana International Science Series written by Heinz Knoepfel and published by Springer. This book was released on 2013-12-19 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the papers presented at the Course on "Tokamak Startup - Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor" which was held in Erice, July 14-20, 1985. The fact that the critical startup and transient phases of a tokamak reactor are now the specific subject of a comprehensive international gathering of fusion specialists seems indicative of the substantial pro gress made in recent years towards attaining controlled ignition of a nuclear fusion fuel, i.e. towards demonstrating the scientific feasibili ty of controlled thermonuclear fusion. In fact, the steady-state burning phase has attracted so far most of the attention of fusion physicists and engineers, as it is conceptually more rewarding, and theoretically easier to handle. However, as for many large engineering systems, - nuclear fis- ... ':1' " . 10 ' ... Entrance to San Rocco's lecturing hall v sion power plants, or aerospace crafts, for example - the major issues of design and operation lie often in the startup, shutdown and power tran sieQt phases, rather than at the full load, or at cruising regimes. In ehoosing the contributions to this 7th Course of Prof. B.
