Download or read book Novel Current Drive Experiments on the CDX U HIT and DIII D Tokamaks written by and published by . This book was released on 1992 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two types of novel, non-inductive current drive concepts for starting-up and maintaining tokamak discharges have been developed on the CDX-U, HIT, and DIII-D Tokamaks. On CDX-U, a new, non-inductive current drive technique utilizing fully internally generated pressure driven currents has been demonstrated. The measured current density profile shows a non-hollow profile which agrees with a modeling calculation including helicity conserving non-classical current transport providing the seed current''. Another current drive concept, dc-helicity injection, has been investigated on, CDX-U, HIT and DIII-D. This method utilizes injection of magnetic helicity via low energy electron currents, maintaining the plasma current through helicity conserving relaxiation. In these experiments, non-ohmic tokamak plasmas were formed and maintained in the tens of kA range.

Download or read book Novel Current Drive Experiments on the CDX U HIT and DIII D Tokamaks written by R. J. Armstrong and published by . This book was released on with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plasma Physics and Controlled Nuclear Fusion Research written by and published by . This book was released on 1992 with total page 808 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1993-02 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies of Non inductive Current Drive in the CDX U Tokamak written by Yong-Seok Hwang and published by . This book was released on 1993 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1993 with total page 1360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lower Hybrid Current Drive Experiments in the HT 7 Tokamak written by Zhongyong Chen and published by Nova Novinka. This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The achievement of steady state operation and long pulse is one of the major challenges in the tokamak plasmas. One of the most effective means to sustain tokamak steady state operation is non-inductive current drive (NICD) by lower hybrid (LH) wave. Lower hybrid current drive (LHCD) as an effective NICD tool has been demonstrated in many tokamaks. LHCD is used to modify the plasma current profile to improve the MHD stability, or used in conjunction with ion Bernstein wave (IBW) to achieve high performance discharge. The achievement of high current drive efficiency is of primary importance since it determines the required power that must be recycled to sustain the plasma current. This book discusses the lower-hybrid current drive experiences currently being done in regards to HT-7 tokamaks.

Download or read book Fast Wave Current Drive Experiment on the DIII D Tokamak written by and published by . This book was released on 1992 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: One method of radio-frequency heating which shows theoretical promise for both heating and current drive in tokamak plasmas is the direct absorption by electrons of the fast Alfven wave (FW). Electrons can directly absorb fast waves via electron Landau damping and transit-time magnetic pumping when the resonance condition [omega] - [kappa]{sub {parallel}e}[upsilon]{sup {parallel}e} = O is satisfied. Since the FW accelerates electrons traveling the same toroidal direction as the wave, plasma current can be generated non-inductively by launching FW which propagate in one toroidal direction. Fast wave current drive (FWCD) is considered an attractive means of sustaining the plasma current in reactor-grade tokamaks due to teh potentially high current drive efficiency achievable and excellent penetration of the wave power to the high temperature plasma core. Ongoing experiments on the DIII-D tokamak are aimed at a demonstration of FWCD in the ion cyclotron range of frequencies (ICRF). Using frequencies in the ICRF avoids the possibility of mode conversion between the fast and slow wave branches which characterized early tokamak FWCD experiments in the lower hybrid range of frequencies. Previously on DIII-D, efficient direct electron heating by FW was found using symmetric (non-current drive) antenna phasing. However, high FWCD efficiencies are not expected due to the relatively low electron temperatures (compared to a reactor) in DIII-D.

Download or read book Lower Hybrid Current Drive Experiments on the Encore Tokamak written by Lawrence Sverdrup and published by . This book was released on 2002 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Annual Index written by and published by . This book was released on 1994 with total page 1190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Current Drive Experiments on the PLT Tokamak written by F. Jobes and published by . This book was released on 1983 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Recent Results from DIII D and Their Implications for Next Generation Tokamaks written by and published by . This book was released on 1990 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent results from the DIII-D tokamak have provided significant contributions to the understanding of many of the elements of tokamak physics and the application of this understanding to the design of next generation devices including ITER and CIT. The limitations of magnetohydrodynamics stability on the values of plasma beta (the ratio of kinetic pressure to the containing pressure of the magnetic field) that can be attained has been experimentally demonstrated and found to be described by existing theory. Values of beta (10.7%) well in excess of those required for proposed devices (ITER and CIT) have been demonstrated. Regimes of confinement (H-mode) have been established that scale favorably to proposed next generation devices, and experiments demonstrating the dependence of the energy confinement on plasma size have been completed. Understanding of confinement is rapidly developing especially in the areas of bulk transport and the role of turbulence in the plasma edge. Key experimental results in areas of plasma transport and edge plasma phenomena are found to be in agreement with theories based on short wavelength turbulence. Control of the divertor heat loads and impurity influx has been demonstrated, and new progress has been made in the understanding of plasma edge phenomena. Experiments with ion Bernstein wave heating have not found regimes in which these waves can produce effective central ion heating. Electron cyclotron current drive experiments have demonstrated 70 kA of driven current in 400 kA discharges.

Download or read book Proyecto de una contribuci n supletoria del diezmo written by and published by . This book was released on 1839 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Current Drive with Fast Waves Electron Cyclotron Waves and Neutral Injection in the DIII D Tokamak written by and published by . This book was released on 1992 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current drive experiments have been performed on the DIII-D tokamak using fast waves, electron cyclotron waves, and neutral injection. Fast wave experiments were performed using a 4-strap antenna with 1 MW of power at 60 MHz. These experiments showed effective heating of electrons, with a global heating efficiency equivalent to that of neutral injection even when the single pass damping was calculated to be as small as 5%. The damping was probably due to the effect of multiple passes of the wave through the plasma. Fast wave current drive experiments were performed with a toroidally directional phasing of the antenna straps. Currents driven by fast wave current drive (FWCD) in the direction of the main plasma current of up to 100 kA were found, not including a calculated 40 kA of bootstrap current. Experiments with FWCD in the counter current direction showed little current drive. In both cases, changes in the sawtooth behavior and the internal inductance qualitatively support the measurement of FWCD. Experiments on electron cyclotron current drive have shown that 100 kA of current can be driven by 1 MW of power at 60 GHz. Calculations with a Fokker-Planck code show that electron cyclotron current drive (ECCD) can be well predicted when the effects of electron trapping and of the residual electric field are included. Experiments on driving current with neutral injection showed that effective current drive could be obtained and discharges with full current drive were demonstrated. Interestingly, all of these methods of current drive had about the same efficiency, 0.015 x 102° MA/MW/m2.

Download or read book First Results on Fast Wave Current Drive in Advanced Tokamak Discharges in DIII D written by and published by . This book was released on 1995 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Initial experiments have been performed on the DIII-D tokamak on coupling, direct electron heating, and current drive by fast waves in advanced tokamak discharges. These experiments showed efficient central heating and current drive in agreement with theory in magnitude and profile. Extrapolating these results to temperature characteristic of a power plant (25 keV) gives current drive efficiency of about 0.3 MA/m2.

Download or read book Electron Cyclotron Current Drive and Current Profile Control in the DIII D Tokamak written by and published by . This book was released on 1998 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent work in many tokamaks has indicated that optimization of the current profile is a key element needed to sustain modes of improved confinement and stability. Generation of localized current through application of electron cyclotron (EC) waves offers a means of accomplishing this. In addition to profile control, electron cyclotron current drive (ECCD) is useful for sustaining the bulk current in a steady state manner and for instability suppression. ECCD is particularly well suited for control of the current profile because the location of the driven current can be regulated by external means, through steering of the incident EC waves and setting the magnitude of the toroidal magnetic field. Under most conditions the location of the driven current is insensitive to the plasma parameters. Central ECCD has been studied in a number of tokamaks and found to have characteristics commensurate with theory as expressed through ray tracing and Fokker-Planck computer codes. The present experiments on DIII-D explore central current drive and are the first to test off-axis ECCD. These experiments are unique in using internal measurements of the magnetic field to determine the magnitude and profile of driven current.