A hybrid digital-analog long pulse integrator

A digital-analog integrator has been developed for use with inductive magnetic sensors in long-pulse tokamaks. Continuous compensation of input offsets is accomplished by alternating analog-to-digital convertor samples from the sensor and a dummy load, while an RC network provides passive integration between samples. Typically a sampling rate of 10 kHz is used. In operational tests on the DIII-D tokamak, digital and analog integration of tokamak data show good agreement. The output drift error during a 1200 s integration interval corresponds to a few percent of the anticipated signal for poloidal field probes in International Thermonuclear Experimental Reactor (ITER), and bench tests suggest that the error can be reduced further.

[1]  M.L. Walker,et al.  A digital long pulse integrator , 1995, Proceedings of 16th International Symposium on Fusion Engineering.

[2]  I. Hutchinson Principles of Plasma Diagnostics , 1987 .