نتایج جستجو برای: current drive
تعداد نتایج: 849350 فیلتر نتایج به سال:
The high-β spherical tokamaks (ST), such as NSTX and MAST, are attractive fusion devices for studying the physics of current drive by electron cyclotron (EC) waves. While ST plasmas are overdense to conventional EC waves, electron Bernstein waves (EBW) can be used to generate plasma currents. Besides providing better confinement, EBW driven current can also help suppress neoclassical tearing mo...
In tokamak plasmas with multiple ion species, fast magnetosonic waves (FW) in the Ion Cyclotron Range of Frequency can mode convert to shorter wavelength modes at the Ion-Ion hybrid layer, leading to localized electron heating and current drive. Due to k‖ upshifts associated with the poloidal magnetic field, only small net driven currents were predicted from mode converted Ion Bernstein Waves (...
A 20 MW/5GHz Lower Hybrid Current Drive (LHCD) system was initially due to be commissioned and used for the second mission of ITER, i.e. the Q=5 steady state target. Though not part of currently planned procurement phase, it is now under consideration for an earlier delivery. In this paper, both physics and technology conceptual designs are reviewed. Furthermore, an appropriate work plan is als...
The channels belonging to the KCNQ gene family consist of 5 different subtypes, which assemble as pentameric channels. The KCNQ2-5 subunits are highly expressed in the ventrobasal thalamus (VB) where they function primarily as KCNQ2/3 heteromers. They underlie an outward potassium (K+)-current, called M-current (IM), which provides a hyperpolarizing drive, thus regulating neuronal excitability....
In this paper, chaotic behavior in current-mode-controlled dc drive systems has been analyzed. The key is to derive an iterative map that describes the nonlinear system dynamics. Analytical modeling of fundamental and subharmonic oscillations as well as their stability analysis are presented. The results show that the current-mode-controlled dc drive systems generally exhibit chaotic behavior. ...
Minority ion cyclotron current drive is studied by solving the FokkerPlanck equation in toroidal geometry keeping the ∂/∂v‖-term in the quasilinear operator, hereby including the important effects of the finite orbit widths of the tail ions and the wave-induced spatial drift and diffusion. It has previously been found that the trapped ion current and the current carried by passing ions detrappe...
Variable frequency devices are widely used in many power systems. A current tracking based VFD is proposed in this paper. The output current is firstly fed back and compared with a standard sine wave, the difference of them is then used for a PI regulator to control the PWM signal, so as to change the output current accordingly to make it approach the standard sine wave. Simulation and experime...
During the last few decades, our lives have been changed dramatically by the unprecedented development of electronic devices, which become faster, more portable and less expensive, yet with more integrated functionalities. This progress was all driven by MOSFET downscaling, doubling the integration density of integrated circuits roughly every two years, as embodied in Moore's law. However, the ...
This work was supported by the U.S. Department of Energy, Grant No. DE-FG02-91ER-54109, by the U.S. Department of Energy jointly with the National Spherical Torus Experiment, Grant No. DE-FG02-99ER-54521, and U.S. Department of Energy, Cooperative Grant No. DE-FC0299ER-54512. Reproduction, translation, publication, use and disposal, in whole or in part, by or for the United States government is...
Fast-wave current drive is demonstrated in Hw Princeton ACT -I toroidal device. The fast Alfven wave, in the range of high ion-cyclotron harmonics, produced 40 A of current from 1 kW of rf power coupled into a plasma hy a fast-wave locp antenna. This wave excites a steady current by damping on the energetic tail of the electron distribution function in the same way as lower-hybrid current drive...
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