The JET Level­1 Software

The complex nature of the JET machine requires a large amount of control parameter preparation, selection and validation before a pulse may be started. Level-1 is defined as the centralised, cross-subsystem control of JET. Before it was introduced over 10 years ago [1], the Session Leader (SL) who is responsible for specifying the parameter settings for a JET pulse, had virtually no software available to help him except for a simple editor used for the creation of control waveforms. Most of the required parameter settings were calculated by hand and then passed on either verbally or via hand-written forms. These parameters were then set by a large number of people - Local Unit Responsible Officers (LUROs) and CODAS Duty Officers (CDOs) using a wide selection of dedicated software. At this time the Engineer in Charge (EiC) would largely depend on the LUROs to inform him that conditions were ready. He never set control parameters personally and had little or no software available to him to see what many of the settings were. The first implementation of Level-1 software went some way towards improving the task of pulse schedule preparation in that the SL could specify his requirements via a computer interface and store them in a database for later use. At that time the maximum number of parameters that could be handled was 500. It was not until the early 1990s when the JET computer system was moved to a UNIX environment that the full potential of Level-1 could be achieved. The present version of level 1 covers nearly 10000 parameters and is used by the SL and EIC for the main plasma control and by LUROs for additional heating, diagnostics, power supplies and real time power control.