Status of the Linux PC cluster for between-pulse data analyses at DIII-D

Some analyses that survey experimental data are carried out at a sparse sample rate between pulses during tokamak operation and/or completed as a batch job overnight because the complete analysis on a single fast workstation cannot fit in the narrow time window between two pulses. Scientists therefore miss the opportunity to use these results to guide experiments quickly. With a dedicated Beowulf type cluster at a cost less than that of a workstation, these analyses can be accomplished between pulses and the analyzed data made available for the research team during the tokamak operation. A Linux PC cluster comprised of 12 processors was installed at DIII-D National Fusion Facility in CY00 and expanded to 24 processors in CY01 to automatically perform between-pulse magnetic equilibrium reconstructions using the efit code written in fortran, cer analyses using cerquick code written in interactive data language (idl) and full profile fitting analyses (ne, Te, Ti, Vr, Zeff) using idl code zipfit. This paper reports the current status of the system, the details of the between-pulse profile fitting analyses, and discusses some problems and concerns raised during the implementation and expansion of the system.