Welcome to High-Temperature Plasma Physics Research Division Homepage
  • Let me introduce our diagnostics activity briefly. The detail explanation on each diagnostics can be seen in the separate pages.
  • A YAG Thomson scattering system for measuring electron temperature and electron density is successfully working routinely. The system can measure the scattered lights at 200 points along a major radius every 20 ms, giving full profiles of electron temperatures and densities. The spatial resolution ranges about 20 mm. ECE for measuring electron temperature profile has three features of detection: Heterodyne radiometer, Michelson inteferometer, and Grating polychrometer (GPC). A FIR interferometer system for measuring electron density using 13 laser beams is working well too. For measuring ion temperature, the array of the charge exchange recombination spectroscopy (CXRS) is working with utilizing the NBI heating beam. The other many diagnostics are also working rather well, and new diagnostic methods are also being intensively developed.
  • The LHD main diagnostics data acquisition system is a decentralized system with the architecture of the object oriented distributed data base. There are two clusters: one is the data acquisition cluster, and the other is the data analysis cluster.
  • We have to take a special care for the real time data acquisition, because we are planning a long pulse discharge for 30 minutes or longer. For this purpose, we are developing a new system.
  • To analyze easily data acquired by the different systems, we constructed a new unifying database for different data acquisition systems. It relies on the index server with the file system for the whole data. This system is working now, and the advanced version is also planned to develop.
  • With all the efforts, I hope the diagnostics group will contribute significantly to the developments of an ideal nuclear fusion reactor.


           IDA Katsumi

           (Director of High-Temperature Plasma Physics Research Division) 

The key issues of diagnostics for LHD are:

  • Capability of multi-dimensional (2-D or 3-D) measurements because of a non-axisymmetric toroidal plasma
  • Advanced measurements with heat removal adequate for high heat flux and steady-state operation
  • An adequate data acquisition system handling large amounts of data for steady-state operation