Development review of transient recorders with onboard isolation on JET

The JET tokamak is currently using about 7000 transient recorder channels for data acquisition, mainly sampling at 5 kHz but including a few at 1 MHz or higher. Nearly half of the channels are provided by module designs with front ends that are galvanically isolated to over 1000 V. Performing analogue-to-digital conversion before isolation provides many benefits. This paper reviews three such designs that have been commissioned or developed by control and data acquisition systems (CODAS) personnel over the past 10 years and examines the trends.