Distributed processing and network of data acquisition and diagnostics control for large helical device (LHD)

The LHD (large helical device) data processing system has been designed in order to deal with the huge amount of diagnostics data of 600 similar to 90 0 MB per 10 s short-pulse experiment. It prepared the first plasma experime nt in March 1998. The recent increase of the data mass obliged to adopt the fully distributed system structure which uses multiple data transfer paths in parallel and categorize all of the computer functions into clients and servers. The fundamental element installed for every diagnostic device cons ists of two kinds of sever computers; the data acquisition PC/Windows NT an d the real-time diagnostics control VME/VxWorks. To cope with diversified k inds of device control channels and diagnostics data, the object-oriented m ethods are utilized wholly for the development of this system. It not only reduces the development burden, but also widen the software portability and flexibility. One hundred Mbps FDDI-based fast networks will re-integrate t he distributed server computers so that they can behave as one virtual macr o-machine for users. Network methods applied for the LHD data processing sy stem are completely based on the TCP/IP internet technology, and it provide s the same accessibility to the remote collaborators as local participants have. (C) 1999 Elsevier Science S.A. All rights reserved.