Author: C. E. BushPublisher:
ISBN:
Category : National Spherical Torus Experiment (Project)
Languages : en
Pages : 34
Book Description
Configuration and Heating Power Dependence of Edge Parameters and H-mode Dynamics in National Spherical Torus Experiment (NSTX).
Author: C. E. BushPublisher:
ISBN:
Category : National Spherical Torus Experiment (Project)
Languages : en
Pages : 34
Book Description
Configuration and Heating Power Dependence of Edge Parameters and H-mode Dynamics in National Spherical Torus Experiment (NSTX).
Author: C. E. BushPublisher:
ISBN:
Category : National Spherical Torus Experiment (Project).
Languages : en
Pages : 34
Book Description
The National Spherical Torus Experiment (NSTX) Research Programme and Progress Towards High Beta, Long Pulse Operating Scenarios
Author: The National Spherical Torus Experiment (NSTX) Research Program and Progress Towards High Beta, Long PulseOperating Scenarios
Author: E. J. SynakowskiPublisher:
ISBN:
Category : National Spherical Torus Experiment (Project).
Languages : en
Pages : 12
Book Description
H-Mode Turbulence, PowerThreshold, ELM, and Pedestal Studies in NSTX.
Author: R. MaingiPublisher:
ISBN:
Category : National Spherical Torus Experiment (Project).
Languages : en
Pages : 12
Book Description
The H-Mode Pedestal and Edge Localized Modes in NSTX.
Author: R. MaingiPublisher:
ISBN:
Category : National Spherical Torus Experiment (Project).
Languages : en
Pages : 8
Book Description
H-Mode Turbulence, Power Threshold, ELM, and Pedestal Studies in NSTX.
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
High-confinement mode (H-mode) operation plays a crucial role in NSTX [National Spherical Torus Experiment] research, allowing higher beta limits due to reduced plasma pressure peaking, and long-pulse operation due to high bootstrap current fraction. Here, new results are presented in the areas of edge localized modes (ELMs), H-mode pedestal physics, L-H turbulence, and power threshold studies. ELMs of several other types (as observed in conventional aspect ratio tokamaks) are often observed: (1) large, Type I ELMs, (2) ''medium'' Type II/III ELMs, and (3) giant ELMs which can reduce stored energy by up to 30% in certain conditions. In addition, many high-performance discharges in NSTX have tiny ELMs (newly termed Type V), which have some differences as compared with ELM types in the published literature. The H-mode pedestal typically contains between 25-33% of the total stored energy, and the NSTX pedestal energy agrees reasonably well with a recent international multi-machine scaling. We find that the L-H transition occurs on a [approx]100 [micro]sec timescale as viewed by a gas puff imaging diagnostic, and that intermittent quiescent periods precede the final transition. A power threshold identity experiment between NSTX and MAST shows comparable loss power at the L-H transition in balanced double-null discharges. Both machines require more power for the L-H transition as the balance is shifted toward lower single null. High field side gas fueling enables more reliable H-mode access, but does not always lead to a lower power threshold e.g., with a reduction of the duration of early heating. Finally the edge plasma parameters just before the L-H transition were compared with theories of the transition. It was found that while some theories can separate well-developed L- and H-mode data, they have little predictive value.
Results of NSTX Heating Experiments
Author: D. MuellerPublisher:
ISBN:
Category : Neutral beams
Languages : en
Pages : 8
Book Description
Profile Modifications Resulting from Early High-harmonic Fast Wave Heating in NSTX.
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Experiments have been performed in the National Spherical Torus Experiment (NSTX) to inject high harmonic fast wave (HHFW) power early during the plasma current ramp-up in an attempt to reduce the current penetration rate to raise the central safety factor during the flattop phase of the discharge. To date, up to 2 MW of HHFW power has been coupled to deuterium plasmas as early as t= 50 ms using the slowest interstrap phasing of k approximately equals 14 m(superscript)-1 (nf= 24). Antenna-plasma gap scans have been performed and find that for small gaps (5-8 cm), electron heating is observed with relatively small density rises and modest reductions in current penetration rate. For somewhat larger gaps (10-12 cm), weak electron heating is observed but with a spontaneous density rise at the plasma edge similar to that observed in NSTX H-modes. In the larger gap configuration, EFIT code reconstructions (without MSE[motional Stark effect]) find that resistive flux consumption is reduced as much as 30%, the internal inductance is maintained below 0.6 at 1 MA into the flattop, q(0) is increased significantly, and the MHD stability character of the discharges is strongly modified.
Characteristics of the First H-mode Discharges in NSTX.
Author: R. MaingiPublisher:
ISBN:
Category : National Spherical Torus Experiment (Project).
Languages : en
Pages :
Book Description