Timing system for neutral beam injection on the DIII-D tokamak

The author describes recent modifications to the DIII-D central timing system hardware and software to allow more flexible and complex timing waveforms than previously available to control NB (neutral beam) injection. In the past, for each plasma discharge, the start time and the pulse duration for each NB source could be set. The new NB timing system allows the experimental session leader to specify more than one pulse for each NB source to make efficient use of multiple physics experiments in a single discharge. Also, pulse trains with programmable duty cycles can be independently specified for each NB source to make NB injection a more useful diagnostic tool. Experimental results using features of the new NB timing system are presented.<>