Author: Yong-Seok HwangPublisher:
ISBN:
Category :
Languages : en
Pages : 228
Book Description
Studies of Non-inductive Current Drive in the CDX-U Tokamak
Author: Yong-Seok HwangNovel Current Drive Experiments on the CDX-U, HIT, and DIII-D Tokamaks
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 8
Book Description
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.
Scientific and Technical Aerospace Reports
Author: Lower Hybrid Current Drive Experiments in the HT-7 Tokamak
Author: Zhongyong ChenPublisher: Nova Novinka
ISBN: 9781616688646
Category : Electromagnetic waves
Languages : en
Pages : 0
Book Description
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.
Non-inductive current drive with suprathermal ions and electrons in reactor grade tokamak plasmas
Author: Dieter EckharttHigh-harmonic Fast Wave Heating Experiments in CDX-U.
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 4
Book Description
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.
Non - Inductive Current Drive in Tokamaks
Author: IAEA Technical CommitteePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Non-Inductive Current Drive Modeling Extending Advanced Tokamak Operation to Steady State
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A critical issue for sustaining high performance, negative central shear (NCS) discharges is the ability to maintain current distributions that are maximum off axis. Sustaining such hollow current profiles in steady state requires the use of non-inductively driven current sources. On the DIII-D experiment, a combination of neutral beam current drive (NBCD) and bootstrap current have been used to create transient NCS discharges. The electron cyclotron heating (ECH) and current drive (ECCD) system is currently being upgraded from three gyrotrons to six to provide more than 3MW of absorbed power in long-pulse operation to help sustain the required off-axis current drive. This upgrade SuPporrs the long range goal of DIII-D to sustain high performance discharges with high values of normalized [beta], [beta]{sub n} = [beta]/(I{sub p}/aB{sub T}), confinement enhancement factor, H, and neutron production rates while utilizing bootstrap current fraction, f{sub bs}, in excess of 50%. At these high performance levels, the likelihood of onset of MHD modes that spoil confinement indicates the need to control plasma profiles if we are to extend this operation to long pulse or steady state. To investigate the effectiveness of the EC system and to explore operating scenarios to sustain these discharges, we use time-dependent simulations of the equilibrium, transport and stability. We explore methods to directly alter the safety factor profile, q, through direct current drive or by localized electron heating to modify the bootstrap current profile. Time dependent simulations using both experimentally determined [1] and theory-based [2] energy transport models have been done. Here, we report on simulations exploring parametric dependencies of the heating, current drive, and profiles that affect our ability to sustain stable discharges.
Novel Current Drive Experiments on the CDX-U, HIT, and DIII-D Tokamaks
Author: R. J. ArmstrongNew Ideas in Tokamak Confinement
Author: Marshall N. RosenbluthPublisher: Springer Science & Business Media
ISBN: 9781563961311
Category : Science
Languages : en
Pages : 514
Book Description
Market: Scientists and students involved in thermonuclear fusion research. Thermonuclear fusion research using the confinement device tokamak represents one of the most prominent science projects in the second half of the 20th century. International Tokamak Community is now committing significant effort and funds to experiments with burning plasma, hot and dense enough to produce significant nuclear fusion reactions. The methods used to enhance tokamak performance have a profound and immediate effect on machine design. This book provides an up-to-date account of research in tokamak fusion and puts forward innovative ideas in confinement physics.