Joint experiments on small tokamaks: edge plasma studies on CASTOR

Abstract

The 1st Joint (Host Laboratory) Experiment on 'joint research using small tokamaks' was carried out using the IPP Prague experimental facility 'CASTOR tokamak'. The main experimental programme was aimed at characterizing the edge plasma in a tokamak by using different advanced diagnostic techniques. It is widely recognized that characterization of phenomena occurring at the plasma edge is essential for understanding the plasma confinement in a tokamak. The edge plasma in small and large scale experiments has many similar features, and the results obtained through detailed measurements in a small flexible device such as CASTOR are in many aspects still relevant to those in large tokamaks. Therefore, it is expected that the results of this joint experiment will have general validity. The radial and poloidal structure of electrostatic turbulence was characterized. The effects of edge biasing were analysed. Radiation fluctuations and profile measurements were performed using fast bolometry. Plasma position measurements were performed using novel Hall sensors.

Effects of negative and positive bias voltages on turbulence characteristics in J-TEXT tokamak

“…After that, the n e increase (figure 2(b)) and the hydrogen alpha emissions (H α ) reduce (figure 2(c)) in both ±300 V, which implies that the global particle confinement improves, due to the particle confinement time being proportional to the ratio of n e /H α [37]. Similarly, the global particle confinement improvements during biasing are also seen in J-TEXT [28] and other devices [15,17,24,38,39]. The changes in densities and temperatures measured by the array LP2 at ∆r = −2 cm (i.e.…”

“…For example, a coherent mode of density fluctuation changes from m = 4 to m = 3 after biasing in TJ-K [29]. Wave-like poloidally-extended structures are observed in CASTOR and the mode number of this structure approximately matches the edge safety factor value [39].…”

Contribution to fusion research from IAEA coordinated research projects and joint experiments

“…Results from small fusion devices obtained during previous JEs and from individual co-ordinated activities are well described in [7][8][9]. Here we present only some selected examples of recent results of significant importance to the mainstream fusion research.…”

Summary of the 19th International Atomic Energy Agency Technical Meeting on ‘Research Using Small Fusion Devices’

“…Gryaznevich reported on the results of Joint Experiments organized in the framework of the IAEA Coordinated Research Project (CRP) on 'Joint Research Using Small Tokamaks' that have been carried out on the tokamaks CASTOR at IPP Prague, Czech Republic (2005), T-10 at RRC 'Kurchatov Institute', Moscow, Russia (2006), at ISTTOK at IST, Lisbon, Portugal (2007), and the most recent one on the TCABR tokamak at the University of São Paulo, Brazil, May 2009. These Joint Experiments have clearly demonstrated that small tokamaks are suitable and important for broad international cooperation, providing the necessary environment and manpower to conduct dedicated joint research programmes [4,5]. The contribution of small tokamaks to the mainstream fusion research in topics such as edge turbulence, improved confinement and diagnostics development can be enhanced through coordinated planning.…”