FPGA based demodulation of laser induced fluorescence in plasmas

TL;DR

This paper introduces an FPGA-based system for real-time photon counting and demodulation of laser-induced fluorescence signals in plasmas, enabling high-frequency plasma measurements with background subtraction.

Contribution

The work presents a novel FPGA implementation for demodulating LIF signals at 1 MHz, allowing real-time plasma ion fluctuation analysis with improved signal processing.

Findings

Successfully demodulated LIF signals at 1 MHz

Enabled real-time plasma ion fluctuation measurements

Demonstrated background subtraction capability

Abstract

We present a field programmable gate array (FPGA)-based system that counts photons from laser-induced fluorescence (LIF) on a laboratory plasma. This is accomplished with FPGA-based up/down counters that demodulate the data, giving a background-subtracted LIF signal stream that is updated with a new point as each laser amplitude modulation cycle completes. We demonstrate using the FPGA to modulate a laser at 1 MHz and demodulate the resulting LIF data stream. This data stream is used to calculate an LIF-based measurement sampled at 1 MHz of a plasma ion fluctuation spectrum.