MDSplus extensions for long pulse experiments

MDSplus is a data acquisition and analysis software package used widely throughout the international fusion research community. It was originally designed for use on pulsed experiments where experiment measurements are typically acquired by external measurement devices with local memory and then gathered by the data system after the pulse has completed. Today, more and more fusion research devices are being constructed which have very long pulse lengths. It is no longer acceptable to wait until the pulse completes before acquiring the measurements and making them available to the researchers. To explore the possibility of adapting MDSplus for use on experiments with long pulses, we have designed and implemented some prototype extensions to make MDSplus more suitable for those types of experiments. These extensions may be applicable in other areas such as data handling for fusion modeling codes. To implement these extensions, an additional API was developed to enable applications to store data incrementally in a node. The data is stored in an indexed linked list of data segments in the MDSplus data file enabling efficient retrieval of subsets of the data within a specified time interval.