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The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages in the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaust from fusion devices. Presently the most promising candidate materials are lithium and gallium. However, lithium has a short liquid state range when compared, for example, with gallium that has essentially better thermal properties and lower vapor pressure. To explore further these properties, ISTTOK tokamak is being used to test the interaction of a free flying, fully formed liquid gallium jet with the plasma. The interacting, 2.3 mm diameter, jet is generated by hydrostatic pressure and has a 2.5 m/s flow velocity. The liquid metal injector has been build to allow the positioning of the jet inside the tokamak chamber, within a 13 mm range. This paper p...

A novel material design in nuclear fusion reactors is proposed based on W-nDiamond nanostructured composites. Generally, a microstructure refined to the nanometer scale improves the mechanical strength due to modification of plasticity mechanisms. Moreover, highly specific grain- boundary area raises the number of sites for annihilation of radiation induced defects. However, the low thermal stability of fine-grained and nanostructured materials demands the presence of particles at the grain boundaries that can delay coarsening by a pinning effect. As a result, the concept of a composite is promising in the field of nanostructure d materials. The hardness of diamond renders nanodiamond dispersions excellent reinforcing and stabilization candidates and, in addition, diamond has extremely high thermal conductivity. Consequently, W-nDiamond nanocomposites are promising candidates for thermally stable first-wall materials. The proposed design involves the production of WAV-nDiamondAV-Cu/Cu layered castellations. The W, W-nDiamond and W-Cu layers are produced by mechanical alloying followed by a consolidation route that combines hot rolling with spark plasma sintering (SPS). Layer welding is achieved by spark plasma sintering. The present work describes the mechanical alloying processsing and consolidation route used to produce W-nDiamond composites, as well as microstructur al features and mechanical properties of the material produced Long term plasma exposure experiments are planned at ISTTOK and at FTU (Frascati).

Plasma spectroscopy is a well established technique for impurities study in fusion plasmas. A brief description of the several spectroscopic systems which have been in operation at ISTTOK is given. In ISTTOK a passive spectroscopy diagnostic system is being used to perform spectral and spatial characterization in the 300–850 nm wavelength range. The system used to perform that work consist essentially of a cooled CCD camera coupled to a half a meter imaging spectrograph with collection optics based on a multi‐fiber set to allow for enhanced spatial resolution. Experimental data is shown underlining typical plasma fusion spectral lines and specific ISTTOK characteristics. A web based data access tool is presented that allows the spectral plasma survey in specific wavelength ranges. The information provided by this survey has been used to select suitable transmission filters for a diagnostic, currently under development, to measure Zeff parameter for ISTTOK plasmas. A description of this diagnostic is also presented.

This paper reviews the recent work developed on ISTTOK. A wide variety of diagnostic tools, instrumentation and systems have been developed demonstrating that small tokamaks can play an important role in the fusion community. Furthermore, a physics programme has been carried out with particular emphasis on the control and characterization of the edge fluctuations. Recently, the ISTTOK programme has also dedicated particular attention to the development of plasma facing components being both liquid metal limiters and nanostructured materials.

This contribution summarizes the current implementation of the time‐of‐flight (TOF) energy analysis for plasma potential measurements by the heavy ion beam diagnostic (HIBD) on the tokamak ISTTOK. The technique is described in detail. The results of the measurements of the ISTTOK plasma potential radial profile are presented. It is proved that the TOF energy analysis is suitable for simultaneous multichannel detection using a multiple cell array detector. With the aim of improving the signal‐to‐noise ratio of the diagnostic, the channeltrons have recently been installed on the “start” and “stop” detectors and preliminary results are discussed.

Active control of plasma position on the ISTTOK tokamak is of extreme importance due to the inherent instability caused by an unfavourable curvature of the external equilibrium magnetic field. The consequences of this instability can be suppressed by applying a dynamic equilibrium field. A digital real‐time plasma position control system for ISTTOK has been developed to perform this task. This system uses magnetic measurements to determine the plasma position and feeds the control signal to power supplies that generate the equilibrium fields. After commissioning, the results obtained have shown some discrepancies between the magnetic plasma position reconstruction and several other diagnostics, such as tomography. This discrepancy at some extent is due to the effect of the external magnetic fields on the poloidal magnetic measurements. This work presents a study that addresses this issue. In a future work it will lead to the development of a corrected plasma position algorithm, aiming at obtaining improved performance of plasma discharges and controlled plasma column displacements.

Remote participation tools exist for video conferencing, document co‐authoring and even for data sharing mainly through graphics. However, no single integrated solution existed to be used, whether in a daily informal basis among few researchers, or as a in more formal virtual gatherings with many participants wanting to share nuclear fusion data coming from heterogeneous databases.CFN is now developing FusionTalk, an open source project consisting of server and client software available to all nuclear fusion research institutes. It is a major complement to FireSignal[l] tools for local and remote experiments, which aims to fill the gap in what video‐conferencing, data access and collaboration is concerned. Using FusionTalk web tools one can access and compare data already available on the web and which is often ignored or difficult to use. FusionTalk data search features allow researchers to easily access not only information on CFN's databases but also in other databases (interfaces are already being dev...

The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages to the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaustion from fusion devices. Presently the most promising materials are Lithium and Gallium. ISTTOK, a small size tokamak, will be used to test the behavior of a liquid Gallium jet in the vacuum chamber and its influence on the plasma. This paper presents a description of the conceived setup as well as experimental results. The liquid Gallium jet is generated by hydrostatic pressure and injected in a radial position close to a moveable stainless steel limiter. Both the jet and the limiter positions are variable allowing for a controlled exposure of the liquid Gallium to the edge plasma. The main components of the Gallium loop are a MHD pump, the liquid metal...