Download or read book High harmonic Fast Wave Heating Experiments in CDX U written by Jonathan Edward Menard and published by . This book was released on 1997 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High harmonic Fast Wave Heating Experiments in CDX U written by and published by . This book was released on 1997 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the primary objectives of the proposed National Spherical Tokamak Experiment (NSTX) is the investigation of very high [beta] regimes. Consequently, finding efficient methods of non-inductive heating and current drive required to heat and sustain such plasmas is of considerable importance. High-frequency fast waves are a promising candidate in this regard. However, in NSTX, the field-line pitch at the outer midplane will range from 0 up to 60 degrees from plasma start-up to current flattop. Thus, antenna strap orientation with respect to the edge magnetic field may have a serious impact on power coupling and absorption. To address this issue, the vacuum vessel of the Current Drive Experiment -- Upgrade (CDX-U) spherical tokamak has been upgraded to accommodate a rotatable two-strap antenna capable of handling several hundred kilowatts in short pulses. Details of the antenna design and results from loading measurements made as a function of power, strap angle, and strap phasing will be presented. Results from microwave scattering experiments will also be discussed.

Download or read book High harmonic Fast Wave Coupling and Heating Experiments in the CDX U Spherical Tokamak written by Jonathan Edward Menard and published by . This book was released on 1998 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Results of High Harmonic Fast Wave Heating Experiments on NSTX written by J. Hosea and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heating and Current Drive on NSTX and HHFW Experiments on CDX U written by J. R. Wilson and published by . This book was released on 1998* with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Harmonic Fast Wave Heating Efficiency Enhancemen and Current Drive at Longer Wavelength on the National Spherical Torus Experiment written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Harmonic Fast Wave Heating in NSTX written by B. P. LeBlanc and published by . This book was released on 2001 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Harmonic Fast Wave Heating Experiments on NSTX written by J. R. Wilson and published by . This book was released on 2000 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigations of Low and Moderate Harmonic Fast Wave Physics on CDX U written by Jeffrey Dario Spaleta and published by . This book was released on 2003 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heating and Current Drive on NSTX and HHFW Experiments on CDX U written by J. R. Wilson and published by . This book was released on 1998 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High harmonic Fast wave Heating in NSTX written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High-Harmonic Fast-Wave (HHFW), a radio-frequency technique scenario applicable to high-beta plasmas, has been selected as one of the main auxiliary heating systems on the National Spherical Torus Experiment (NSTX). The HHFW antenna assembly comprises 12 toroidally adjacent current elements, extending poloidally and centered on the equatorial plane. This paper reviews experimental results obtained with a symmetrical (vacuum) launching spectrum with k= 14 m(superscript ''-1'') at a frequency of 30 MHz. We describe results obtained when HHFW power is applied to helium and deuterium plasmas, during the plasma-current flattop period of the discharge. Application of 1.8-MW HHFW pulse to MHD quiescent plasmas resulted in strong electron heating, during which the central electron temperature T(subscript ''eo'') more than doubled from approximately 0.5 keV to 1.15 keV. In deuterium plasmas, HHFW heating was found less efficient, with a central electron temperature increase of the order of 40% during a 1.8-MW HHFW pulse, from approximately 400 eV to approximately 550 eV. (At HHFW power of 2.4 MW, central electron temperature increased by 60%, reaching 0.625 keV.) HHFW heating in presence of MHD activity is also discussed. A short neutral-beam pulse was applied to permit charge-exchange recombination spectroscopy (CHERS) measurement of the impurity ion temperature T(subscript ''i''). Preliminary CHERS analysis show that ion temperature approximately equals electron temperature during HHFW heating. Of special interest are deuterium discharges, where the application of HHFW power was done during the current ramp-up. We observe the creation of large density gradients in the edge region. In the latter case, the density rose spontaneously to n (subscript ''eo'') less than or equal to 8 x 10 (superscript ''13'') cm (superscript ''-3'').

Download or read book Current Trends in International Fusion Research written by National Research Council Canada and published by NRC Research Press. This book was released on 2002 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High harmonic Ion Cyclotron Heating and Current Drive in Ultra small Aspect Ratio Tokamaks written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra-small aspect ratio tokamaks present a totally new plasma environment for heating and current drive experiments and involve a number of physics issues that have not previously been explored. These devices operate at low magnetic field and relatively high density so that the effective dielectric constant of the plasma to high harmonic fast waves (HHFW), is quite high, and perpendicular wavelength of fast waves is very short.[lambda][approximately] 2.0 cm compared with[lambda] - 10-20 cm. This makes possible strong electron absorption at high harmonics of the ion cyclotron frequency, [Omega][sub i], and at fairly high phase velocity in relation to electron thermal velocity. If the antenna system can control the parallel wave spectrum, this offers the promise of high efficiency off-axis current drive and the possibility for current drive radial profile control. Antenna phasing is ineffective for profile control in conventional tokamaks because of central absorption. There are also challenges for antenna design in this regime because of the high dielectric constant and the large angle of the magnetic field with respect to the equatorial plane ([approximately]45[degrees]), which varies greatly during current ramp. Preliminary experiments in this HHFW regime are being carried out in CDX-U.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1998 with total page 790 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determination of Equilibrium and Stability Characteristics of Low aspect Ratio Spherical Torus Plasmas in the PEGASUS Toroidal Experiment written by Sontag Aaron and published by . This book was released on 2002 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Edge Ion Heating by Launched High Harmonic Fast Waves in NSTX written by T. M. Biewer and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electron Cyclotron Emission And Electron Cyclotron Heating Ec12 Proceedings Of The 12th Joint Workshop written by Gerardo Giruzzi and published by World Scientific. This book was released on 2003-02-21 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 12th Joint Workshop on Electron Cyclotron Emission and Electron Cyclotron Resonance Heating (EC-12) was held in Aix-en-Provence (France) from May 13 to 16, 2002. This workshop was concerned with the interaction of electromagnetic waves and hot plasmas, a subject of great importance in the framework of research on controlled thermonuclear fusion. Using as a fuel a mixture of deuterium and tritium, which can be extracted from sea water, this is a very promising way to develop an intrinsically safe reactor. The workshop gathered approximately one hundred specialists in the production, use and theory of millimetre waves for heating and diagnostics of fusion plasmas.