Signal conditioning electronics and packaging for the Alcator C-MOD tokamak

Abstract

A design utilizing industry-standard EURO card packaging, connected via ribbon cable to a custom I/O backplane, accommodates the many different circuits to be used on Alcator C-MOD. The chassis approach eliminates packaging, powering, and mounting problems associated with one-of-a-kind circuits and allows dense packaging of multiple circuits. The separate I/O backplane allows easy removal and replacement of circuit cards, while leaving front panel space available for circuit-specific indicators. The DIN pin-and-socket connectors are considerably more robust and reliable than edge connectors. The pin-out allows up to four circuits per card, allowing up to eighty channels in one 5-1/2-in-tall, rack mountable chassis. A variety of general-purpose signal conditioning circuit cards was designed and built for engineering and diagnostic systems. Four channel circuits include low-drift integrators, analog multiplexers, temperature controllers, instrumentation amplifiers, transimpedance amplifiers, and an eight-pole Bessel filter for anti-aliasing applications. A two-channel card provides thermal electric cooler control. Fiber-optic interface is provided by an 8-b digital transceiver and an analog fiber-optic link.<>