Pulse Reflectometer and Doppler back-scattering diagnostics in the TCV Tokamak

Latest DBS and Pulse reflectometer developments in the TCV tokamak are presente

Demonstration of Electron-Bernstein-Wave Heating in a Tokamak via O-X-B Double-Mode Conversion

The first demonstration of electron-Bernstein-wave heating by double-mode conversion from the O to the X mode in an overdense H-mode tokamak plasma has been achieved in the Tokamak a` Configuration Variable device. This technique overcomes the upper density limit experienced by conventional microwave heating. The sensitive dependence of the O-X mode conversion on the microwave launching direction has been verified experimentally, and localized power deposition consistent with theoretical predictions has been observed at densities well above the conventional cutoff

Electron Bernstein wave heating of over-dense H-mode plasmas in the TCV tokamak via O-X-B double mode conversion

This paper reports on the first demonstration of electron Bernsteinwave heating (EBWH) by double mode conversion from ordinary (O-) to Bernstein (B-) via the extraordinary (X-) mode in an over-dense tokamak plasma, using low field side launch, achieved in the TCV tokamak H-mode, making use of its naturally generated steep density gradient. This technique offers the possibility of overcoming the upper density limit of conventional EC microwave heating. The sensitive dependence of the O-X mode conversion on the microwave launching direction has been verified experimentally. Localized power deposition, consistent with theoretical predictions, has been observed at densities well above the conventional cut-off. Central heating has been achieved, at powers up to two megawatts. This demonstrates the potential of EBW in tokamak H-modes, the intended mode of operation for a reactor such as ITER

Recent progress in the upgrade of the TCV EC-system with two 1MW/2s dual-frequency (84/126GHz) gyrotrons

The upgrade of the EC-system of the TCV tokamak has entered in its realization phase and is part of a broader upgrade of TCV. The MW-class dual-frequency gyrotrons (84 or 126GHz/2s/1MW) are presently being manufactured by Thales Electron Devices with the first gyrotron foreseen to be delivered at SPC by the end of 2017. In parallel to the gyrotron development, for extending the level of operational flexibility of the TCV EC-system the integration of the dual-frequency gyrotrons adds a significant complexity in the evacuated 63.5mm-diameter HE11 transmission line system connected to the various TCV low-field side and top launchers. As discussed in [1], an important part of the present TCV-upgrade consists in inserting a modular closed divertor chamber. This will have an impact on the X3 top-launcher which will have to be reduced in size. For using the new compact launcher we are considering employing a Fast Directional Switch (FADIS), combining the two 1MW/126GHz/2s rf-beams into a single 2MW rf-beam

Transport and turbulence reduction with negative triangularity : Correlation ECE measurements in TCV

Turbulence and Transport Reduction with Negative Triangularity : Correlation ECE Measurements in TCV Due to turbulence, core energy transport in fusion devices such as tokamaks generally exceeds collisional transport by at least an order of magnitude. It is therefore crucial to understand the instabilities driving the turbulent state and to find ways to control them. Plasma shape is one of these fundamental tools. In low collisionality plasmas, such as in a reactor, changing the plasma shape from Dee-shape to inverse Dee-shape (from positive to negative triangularity δ) reduces the energy transport by a factor two: the heat flux necessary to sustain the same profiles and stored energy in a discharge with δ=-0.4 is only half of that at δ=+0.4. This is significant, since it opens the possibility of having Hmode-like confinement time within an L-mode edge; or at least with smaller ELMs. Recent correlation ECE measurements show that this reduction of transport at negative δ is reflected in a reduction by a factor of two of both 1) the amplitude of temperature fluctuations in the broadband frequency range 30-150 kHz, and 2) the fluctuation correlation length, measured at mid-radius (ρv~0.6). In addition, the fluctuations amplitude is reduced with increasing collisionality, consistent with theoretical estimates of the collisionality effect on Trapped Electron Modes (TEM). The correlation ECE results are compared to gyrokinetic code results: 1) global linear gyrokinetic simulations (LORB) have predicted shorter radial TEM wavelength λ⊥ for negative triangularity plasmas, consistent with the shorter radial turbulence correlation length λc observed. 2) At least close to the strongly shaped plasma boundary, local nonlinear gyrokinetic simulations with the GS2 code predict that the TEM induced transport decreases with decreasing triangularity and increasing collisionality, in fair agreement with the experimental observations. 3) Calculations are now extended to global nonlinear simulations (ORB5). This work was supported in part by the Swiss National Science Foundatio

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field