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Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
Initial experiments on heating and current drive using second harmonic electron cyclotron heating (ECH) are being performed on the DIII-D tokamak using the new 110 GHz ECH system. Modulation of the ECH power in the frequency range 50 to 300 Hz and detection of the temperature perturbation by ECE diagnostics is used to validate the location of the heating. This technique also determines an upper bound on the width of the deposition profile. Analysis of electron cyclotron current drive indicates that up to 0.17 MA of central current is driven, resulting in a negative loop voltage near the axis.
Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
Initial experiments on heating and current drive using second harmonic electron cyclotron heating (ECH) are being performed on the DIII-D tokamak using the new 110 GHz ECH system. Modulation of the ECH power in the frequency range 50 to 300 Hz and detection of the temperature perturbation by ECE diagnostics is used to validate the location of the heating. This technique also determines an upper bound on the width of the deposition profile. Analysis of electron cyclotron current drive indicates that up to 0.17 MA of central current is driven, resulting in a negative loop voltage near the axis.
Author: Publisher: ISBN: Category : Languages : en Pages : 17
Book Description
Electron cyclotron current drive has been demonstrated on the DIII-D tokamak in an experiment in which (approximately)1 MW of microwave power generated (approximately)50 kA of non-inductive current. The rf-generated portion was about 15% of the total current. On the T-10 tokamak, more than 3 MW of microwave power will be available for current generation, providing the possibility that all the plasma current could be maintained by this method. Fokker-Planck calculations using the code CQL3D and ray tracing calculations using TORAY have been performed to model both experiments. For DIII-D the agreement between the calculations and measurements is good, producing confidence in the validity of the computational models. The same calculations using the T-10 geometry predict that for n{sub e}(0) (approximately) 1.8 x 1013 cm−3, and T{sub e}(0) (approximately) 7 keV, 1.2 MW, that is, the power available from only three gyrotrons, could generate as much as 150 kA of non-inductive current. Parameter space scans in which temperature, density and resonance location were varied have been performed to indicate the current drive expected under different experimental conditions. The residual dc electric field was considered in the DIII-D analysis because of its nonlinear effect on the electron distribution, which complicates the interpretation of the results. A 110 GHz ECH system is being installed on DIII-D. Initial operations, planned for late 1991, will use four gyrotrons with 500 kW each and 10 second output pulses. Injection will be from the low field side from launchers which can be steered to heat at the desired location. These launchers, two of which are presently installed, are set at 20 degrees to the radial and rf current drive studies are planned for the initial operation. 8 refs., 10 figs.
Author: Gerardo Giruzzi Publisher: World Scientific ISBN: 9814487295 Category : Science Languages : en Pages : 613
Book Description
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.
Author: John Lohr Publisher: World Scientific ISBN: 9814470996 Category : Science Languages : en Pages : 583
Book Description
These proceedings present the latest results in electron cyclotron emission, heating and current drive, with an emphasis on the physics and technology of Electron Cyclotron Emission, Electron Cyclotron Heating and Electron Cyclotron Current Drive applied to magnetic fusion research. The field is a key element in the development of fusion power and the ITER project now under construction.
Author: Publisher: ISBN: Category : Languages : en Pages : 9
Book Description
Fast wave current drive and electron cyclotron current drive experiments have been performed on the DIII-D tokamak as part of the advanced tokamak program. The goal of this program is to develop techniques for controlling the profile of the current density in order to access regimes of improved confinement and stability. The experiments on fast wave current drive used a four strap antenna with 900 phasing between straps. A decoupler was used to help maintain the phasing, and feedback control of the plasma position was used to keep the resistive loading constant. RF pickup loops demonstrate that the directivity of the antenna is as expected. Plasma currents up to 0.18 MA were driven by 1.5 MW of fast wave power. Electron cyclotron current drive experiments at 60 GHz have shown 0.1 MA of plasma current driven by 1 MW of power. New fast wave and electron cyclotron heating systems are in development for DIII-D, so that the goals of the advanced tokamak program can be carried out.
Author: John Lohr Publisher: World Scientific ISBN: 9812814647 Category : Science Languages : en Pages : 583
Book Description
These proceedings present the latest results in electron cyclotron emission, heating and current drive, with an emphasis on the physics and technology of Electron Cyclotron Emission, Electron Cyclotron Heating and Electron Cyclotron Current Drive applied to magnetic fusion research. The field is a key element in the development of fusion power and the ITER project now under construction.
Author: Publisher: ISBN: Category : Languages : en Pages : 18
Book Description
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.
Author: John Lohr Publisher: World Scientific ISBN: 9814548979 Category : Languages : en Pages : 678
Book Description
The conference proceedings will include the papers of approximately 50 key specialists from most of the world's major fusion laboratories, including the European Community, the U.S., Russia and the PRC. The unifying themes are the emission of electron cyclotron waves by high temperature plasmas and the reciprocal process, absorption, which can be used for heating, non inductive current drive and diagnostic purposes.
Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
Electron Cyclotron Current Drive (ECCD) experiments on the DIII-D tokamak have been performed using 60 GHz waves launched from the high field side of the torus. Preliminary analysis indicates rf driven currents between 50 and 100 kA in discharges with total plasma currents between 200 and 500 kA. These are the first ECCD experiments with strong first pass absorption, localized deposition of the rf power, and [tau]{sub E} much longer than the slowing-down time of the rf generated current carriers. The experimentally measured profiles for T{sub e}, [eta]{sub e} and Z{sub eff} are used as input for a 1D transport code and a multiply-ray, 3D ray tracing code. Comparisons with theory and assessment of the influence of the residual electric field, using a Fokker-Planck code, are in progress. The ECH power levels were between 1 and 1.5 MW with pulse lengths of about 500 msec. ECCD experiments worldwide are motivated by issues relating to the physics and technical advantages of the use of high frequency rf waves to drive localized currents. ECCD is accomplished by preferentially heating electrons moving in one toroidal direction, reducing their collisionality and thereby producing a non-inductively driven toroidal current. 6 refs., 4 figs.
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