Abstract
•Microwave interferometer for plasma diagnostics.•Efficient phase detection algorithm for measurement of electron density of plasma.•High speed data acquisition system.•Phase locked loop system for the stable frequency generation.
The design and development of a processing unit for the microwave interferometer is proposed here. The Microwave interferometer is well known for its use in several applications, and one of them is to measure the electron density of fusion plasma. An indigenous effort has been made to build a phase detection system that can be used to calculate fusion plasma electron density for millimeter-wave interferometer. It consists of oven-controlled crystal oscillator (OCXO), frequency synthesizer, IQ mixer, analog to digital converter (ADC), field-programmable gate array (FPGA) for processing the task and other proximity electronics. The phase-detection algorithm is derived using MATLAB. Testing and hardware realization is achieved by implementing it on an FPGA-based system. All the relevant system development requirements are attained with more than 95 percent accuracy. The device will be used in ADITYA tokamak for calculating electron plasma density.