Assessment of the ITER high-frequency magnetic diagnostic set

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The impact of the bootstrap current (BC) has become an important issue in the modeling of quasi-symmetric stellarator devices. Magnetohydrodynamic equilibria have been calculated with self-consistent BC in the collisionless l/nu regime for characteristic quasi-symmetric configurations: a three-period quasi-axisymmetric and a four-period quasi-helically symmetric stellarator. The relationship between magnetic geometry and BC is shown along with its effect on the equilibrium when beta is increased. The releva

A pair of toroidally localized in-vessel antennas in Alcator C-Mod were used to excite and detect stable toroidal Alfven eigenmode (TAE) resonances in the frequency range of 400-500 kHz. By ramping the toroidal field, the plasma TAE frequency was swept through the constant antenna excitation frequency to find a resonance and the width of the resonance was measured to determine the effective damping rate of the mode. The toroidal field and density at the resonances were observed to scale as B-T proportional

This paper shows the importance and feasibility of real-time tomography in fusion experiments for the example of soft X-ray (SXR) position measurements. The requirement of non-magnetic real-time diagnostics in low frequencies for ITER is discussed. This is illustrated by recent results of rapid tomographic inversion of SXR measurements on tokamak TCV. Comparison with the magnetic reconstruction data has not only shown the valuable resolution capabilities of both techniques, but also revealed a slight depend

Interaction of waves in the ion cyclotron range of frequencies (ICRF) with a plasma has a number of key properties that make them attractive beyond pure heating. First, the waves can interact resonantly with either the plasma ions or electrons. In the case of ion cyclotron damping, a small number of resonant ions are often accelerated to high energies. These ions, apart from heating the bulk plasma via Coulomb collisions, can increase fusion reactivity, affect plasma stability and drive current. They have a

Prototype conductors for the ITER magnets have been tested extensively in the SULTAN facility at CRPP in the last decade. The in-depth characterization of the high current carrying conductors provided a valuable feedback in the design, with performance optimization and cost reduction. From the transient stability results on full size, short length conductor samples, the temperature margin required to withstand the plasma disruption has been found to be much smaller than originally assumed. A comparison betw

A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalized plasma pressure for triggering of NTMs, beta(Nonset), is increased. The scenario has been explored experimentally in the Joint European Torus (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance hav

Magnetohydrodynamic (MHD) instabilities can limit the performance and degrade the confinement of tokamak plasmas. The Tokamak à Configuration Variable (TCV), unique for its capability to produce a variety of poloidal plasma shapes, has been used to analyse various instabilities and compare their behaviour with theoretical predictions. These instabilities are perturbations of the magnetic field which usually extend to the plasma edge where they can be detected with magnetic pick-up coils as magnetic fluctuat

An electron cyclotron resonance heating (ECRH) system is presently under construction at Commissariat A l'Energie Atomique (CEA) Cadarache for the Tore Supra experiment. The generator is planned to be made of six gyrotrons giving RF waves with a frequency of 118 GHz and a unit power of 400 kW (500 kW) for a pulse length of 210 s (5 s); two of them are already installed: the prototype was first tested on various dummy loads and on plasma and the first series tube is still being tested on a CW load. The resul

A large variety of shaped tokamak discharges have been created in the Tokamak a Configuration Variable (TCV) with main parameters B-T

An analysis of the effect on the wall stabilization of external kink modes due to toroidally continuous gaps in the resistive wall is performed. The effects both with and without toroidal rotation are studied. For a high-beta equilibrium, the mode structure is localized on the outboard side. Therefore, outboard gaps greatly increase the growth rate when there is no rotation. For resistive wall stabilization by toroidal rotation, the presence of gaps has the same effect as moving the wall farther away, i.e.,

This paper presents an overview of results of the 1994/95 experimental campaign on JET with the new pumped divertor and draws implications for ITER in the areas of detached and radiative divertor plasmas, the use of beryllium as a divertor target the material, the confinement properties of discharges with the same dimensionless parameters (except for the dimensionless Larmor radius) as ITER and the effect of varying the toroidal magnetic field ripple in the ITER relevant range. Discharges with high fusion p

Ohmic H-mode has been regularly obtained on the TCV tokamak. This paper describes the change in magnetic activity occuring at the transition, the coherent activity during H-mode, a brief description of the dithering phase, and the activity associated with large and grassy ELMs.

Assessment of the ITER high-frequency magnetic diagnostic set

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Bootstrap current and quasi-symmetry in reactor-size stellarators

Initial active MHD spectroscopy experiments exciting stable Alfven eigenmodes in Alcator C-Mod

Present and perspective roles of soft X-ray tomography in tokamak plasma position measurements

Application of ICRF waves in tokamaks beyond heating

Recent results from R&D on superconductors at CRPP

Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET

MHD stability limits in the TCV tokamak

The 118 GHz ECRH experiment on Tore Supra

"Profile consistency" features in strongly shaped Ohmic tokamak plasmas

The effect of partial poloidal wall sections on the wall stabilization of external kink modes

JET results with the new pumped divertor and implications for ITER

Mhd Activity During H-Mode Discharges on the Tcv Tokamak