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Enhancement Of Localized Icrf Heating And Current Drive In Tftr D T Plasmas
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Book Synopsis Enhancement of Localized ICRF Heating and Current Drive in TFTR D-T Plasmas by :
Download or read book Enhancement of Localized ICRF Heating and Current Drive in TFTR D-T Plasmas written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical advantages have led to an increased importance of the modification and sustainment of pressure and magnetic shear profiles in plasmas. We have demonstrated electron heating and current drive in TFTR (Tokamak Fusion Test Reactor) plasmas with the existing 43/63.6 MHz ICRF (ion cyclotron range of frequencies) system, both via the fast wave and via mode conversion of the fast wave to an ion-Bernstein wave. In order to achieve both on- and off-axis mode conversion in a pure D-T (deuterium-tritium) plasma, we have changed the operating frequency of two of our transmitters and antennas to 30 MHz and improved the launched directional wave spectrum. As a second step, two new four-strap fast-wave antennas have been installed, and a new four-strap direct-launch IBW antenna has been added as well. This reconfiguration and the resulting operating characteristics of the TFTR ICRF system in a variety of discharges will be presented.
Book Synopsis ICRF Heating and Current Drive Experiments on TFTR. by : J. H. Rogers
Download or read book ICRF Heating and Current Drive Experiments on TFTR. written by J. H. Rogers and published by . This book was released on 1996* with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Perspectives Gained from ICRF Physics Studies on TFTR. by : C. K. Phillips
Download or read book Perspectives Gained from ICRF Physics Studies on TFTR. written by C. K. Phillips and published by . This book was released on 1998* with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Two Frequency ICRF Heating of D-T Plasmas on TFTR. by :
Download or read book Two Frequency ICRF Heating of D-T Plasmas on TFTR. written by and published by . This book was released on 1993 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modifications have been made to allow two of the ICRF antennas (bays L and M) on TFTR to operate at either of two frequencies, 43 MHz or 64 MHz. This was accomplished by lengthening the resonant loops feeding the antennas (2[lambda] at 43 MHz, 3[lambda] at 64 MHz) and replacing the conventional quarter wave impedance transformers with a tapered impedance design. The other two antennas (bays K and N) will operate at a fixed frequency, 43 MHz. The two frequency operation allows a combination of 3He-minority (or T second harmonic) and H-minority heating at full toroidal field on TFIR. Multiple frequency operation may also be useful in direct electron heating and current drive experiments. Other modifications have been made which are expected to permit arbitrary phasing between the current straps on bays M and L. The system design of the antenna, resonant loops and impedance matching system as well as preliminary TFTR results are discussed.
Book Synopsis ICRF Heating and Current Drive Experiments on TFTR. by : J. H. Rogers
Download or read book ICRF Heating and Current Drive Experiments on TFTR. written by J. H. Rogers and published by . This book was released on 1996 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis ICRF Heating of TFTR Deuterium Supershot Plasmas in the 3He Minority Regime by :
Download or read book ICRF Heating of TFTR Deuterium Supershot Plasmas in the 3He Minority Regime written by and published by . This book was released on 1993 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increased core electron temperature produced by ICRF heating of TFTR, D-T neutral-beam-heated supershot plasmas is expected to extend the alpha particle slowing down time and hence enhance the central alpha particle pressure. In preparation for the TFTR D-T operational phase, which is due to start in late 1993, a series of experiments were conducted on TFTR to explore the effect of ICRF heating on the performance and stability of low recycling, deuterium supershot plasmas in the 3He minority heating regime. The coupling of up to 7.4 MW of 47 MHz ICRF power to full size, 3He minority, deuterium supershots heated with up to 30 MW of deuterium neutral beam injection has resulted in a significant increase in core electron temperature. Simulations of equivalent D-T supershots predict that such ICRF heating should result in approximately a 60% increase in the alpha particle slowing down time and an enhancement of about 30% in the central alpha pressure. Future experiments to be conducted at ICRF powers up to 12.5 MW during the upcoming TFTR D-T campaign may result in even greater enhancements in core alpha parameters. This paper presents results from experiments performed at an axial toroidal magnetic field of (approximately)4.8T, where the minority resonance was within 0.1--0.15 m of the plasma core. Combined ICRF and neutral beam heating powers in these experiments reached TFTR record levels of over 37 MW, which allowed an exploration of the power loading limits on the carbon limiter tiles. The plasma current was operated at 1.85 and 2.2 MA and sawtooth suppression was observed at the higher plasma current.
Book Synopsis Two Frequency ICRF Heating of D-T Plasmas on TFTR. by : J. Hosea
Download or read book Two Frequency ICRF Heating of D-T Plasmas on TFTR. written by J. Hosea and published by . This book was released on with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis ICRF Heating of Deuterium-tritium Plasmas in TFTR. by :
Download or read book ICRF Heating of Deuterium-tritium Plasmas in TFTR. written by and published by . This book was released on 1994 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first experiments to heat D-T plasmas in the ion cyclotron range of frequencies (ICRF) have been performed on the Tokamak Fusion Test Reactor (TFTR). These experiments have two major objectives: to study the RF physics of ICRF-heated D-T plasmas and to enhance the performance of D-T discharges. Experiments have been conducted at 43 MHz with out-of-phase current strap excitation to explore n{sub T}/n{sub e} concentrations up to approximately 40%. In these experiments n{sub T}/n{sub e} was limited by D recycling from the carbon walls. The location of the T resonance was varied by changing the toroidal magnetic field, and the RF power was modulated (f{sub mod} = 5--10 Hz) to elucidate competing heating mechanisms. Up to 5.8 MW of ICRF heating has been coupled into D-T plasmas. The addition of 5.5 MW of ICRF heating on a D-T supershot resulted in an increase in central ion temperature from 26 to 36 keV and an increase in central electron temperature from 8 to 10.5 keV. Up to 80% of the absorbed ICRF power was coupled directly to ions, in good agreement with computer code predictions. These results extrapolate to efficient T heating in future devices such as ITER.
Book Synopsis ICRF Heating and Current Drive in TFTR Supershot Plasmas by :
Download or read book ICRF Heating and Current Drive in TFTR Supershot Plasmas written by and published by . This book was released on 1993 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The relevance of rf-sheath-plasma interactions to ICRF operation in TFTR has been studied. Screen-screen and screen-limiter rf sheaths have been identified and analyzed for the old and new Bay M geometries on TFIR, including sheath voltages driven by both feeders and the central antenna conductor. Calculations have been carried out to determine the effects of ICRF on edge transport (profile flattening by E × B convection), impurity influx ([delta]Z{sub eff}) and edge electron heating (FS glow phenomena) as a function of edge plasma parameters, rf power and antenna phasing. It was found that many of the experimentally observed ICRF-edge plasma interactions on TFIR are consistent with the predictions of rf sheath theory.
Book Synopsis ICRF Heating and Transport of Deuterium-tritium Plasmas in TFTR. by :
Download or read book ICRF Heating and Transport of Deuterium-tritium Plasmas in TFTR. written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes results of the first experiments utilizing high-power ion cyclotron range of frequency (ICRF) to heat deuterium-tritium (D-T) plasmas in reactor-relevant regimes on the Tokamak Fusion Test Reactor (TFTR). Results from these experiments have demonstrated efficient core, second harmonic, tritium beating of D-T supershot plasmas with tritium concentrations ranging from 6%-40%. Significant direct ion heating on the order of 60% of the input radio frequency (rf) power has been observed. The measured deposition profiles are in good agreement with two-dimensional modeling code predictions. Energy confinement in an rf-heated supershot is at least similar to that without rf, and possibly better in the electron channel. Efficient electron heating via mode conversion of fast waves to ion Bernstein waves (IBW) has been demonstrated in ohmic, deuterium-deuterium and DT-neutral beam injection plasmas with high concentrations of minority 3He (n{sub 3He}/n{sub e} = 15% - 30%). By changing the 3He concentration or the toroidal field strength, the location of the mode-conversion radius was varied. The power deposition profile measured with rf power modulation indicated that up to 70% of the power can be deposited on electrons at an off-axis position. Preliminary results with up to 4 MW coupled into the plasma by 90-degree phased antennas showed directional propagation of the mode-converted IBW. Analysis of heat wave propagation showed no strong inward thermal pinch in off-axis heating of an ohmically-heated target plasma in TFTR.
Book Synopsis Physics of High Performance Deuterium-tritium Plasmas in TFTR. by : K. M. McGuire
Download or read book Physics of High Performance Deuterium-tritium Plasmas in TFTR. written by K. M. McGuire and published by . This book was released on 1996 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis ICRF Heating During DT Experiments on TFTR by : J. Hosea
Download or read book ICRF Heating During DT Experiments on TFTR written by J. Hosea and published by . This book was released on 1994 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Physics of High Performance Dueterium-Tritium Plasmas in TFTR. by :
Download or read book Physics of High Performance Dueterium-Tritium Plasmas in TFTR. written by and published by . This book was released on 1996 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past two years, deuterium-tritium (D-T) plasmas in the Tokamak Fusion Test Reactor (TFTR) have been used to study fusion power production, isotope effects associated with tritium fueling, and alpha-particle physics in several operational regimes. The peak fusion power has been increased to 10.7 MW in the supershot mode through the use of increased plasma current and toroidal magnetic field and extensive lithium wall conditioning. The high-internal-inductance (high -li) regime in TFTR has been extended in plasma current and has achieved 8.7 MW of fusion power. Studies of the effects of tritium on confinement have now been carried out in ohmic, NBI- and ICRF-heated L-mode and reversed-shear plasmas. In general, there is an enhancement in confinement time in D-T plasmas which is most pronounced in supershot and high-li discharges, weaker in L-mode plasmas with NBI and ICRF heating and smaller still in ohmic plasmas. In reversed-shear discharges with sufficient deuterium-NBI heating power, internal transport barriers have been observed to form, leading to enhanced confinement. Large decreases in the ion heat conductivity and particle transport are inferred within the transport barrier. It appears that higher heating power is required to trigger the formation of a transport barrier with D-T NBI and the isotope effect on energy confinement is nearly absent in these enhanced reverse-shear plasmas. Many alpha-particle physics issues have been studied in the various operating regimes including confinement of the alpha particles, their redistribution by sawteeth, and their loss due to MHD instabilities with low toroidal mode numbers. In weak-shear plasmas, alpha-particle destabilization of a toroidal Alfven eigenmode has been observed.
Book Synopsis Recent Results from the TFTR ICRF DT Program by : J. H. Rogers
Download or read book Recent Results from the TFTR ICRF DT Program written by J. H. Rogers and published by . This book was released on 1995 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis ICRF Heating During DT Experiments on TFTR by : J. Hosea
Download or read book ICRF Heating During DT Experiments on TFTR written by J. Hosea and published by . This book was released on 1994 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis ICRF Heating of Deuterium-tritium Plasmas in TFTR. by : H. G. Adler
Download or read book ICRF Heating of Deuterium-tritium Plasmas in TFTR. written by H. G. Adler and published by . This book was released on 1994 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Upgrade of the DIII-D RF Systems by :
Download or read book Upgrade of the DIII-D RF Systems written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The DIII-D Advanced Tokamak Program requires the ability to modify the current density profile for extended time periods in order to achieve the improved plasma conditions now achieved with transient means. To support this requirement DIII-D has just completed a major addition to its ion cyclotron range of frequency (ICRF) systems. This upgrade project added two new fast wave current drive (FWCD) systems, with each system consisting of a 2 MW, 30 to 120 MHz transmitter, an all ceramic insulated transmission line, and water-cooled four-strap antenna. With this addition of 4 MW of FWCD power to the original 2 MW, 30 to 60 MHz capability, experiments can be performed with centrally localized current drive enhancement. For off-axis current modification, plans are in place to add 110 GHz electron cyclotron heating (ECH) power to DIII-D. Initially, 3 MW of power will be available with plans to increase the power to 6 MW and to 10 MW.
