Continuous-Wave Laser Thomson Scattering Diagnostic for Low Temperature Plasmas

该项目旨在开发一种新的诊断方法，以定量研究低温等离子体中的电子布居。 等离子体，通常被称为物质的第四状态，是一种包含带电物质（如电子和离子）的气体。 低温等离子体也包含高能原子和分子，称为自由基，可以实现许多技术应用。 低温等离子体的性质在很大程度上由电子决定，等离子体科学中的一个持续挑战是开发诊断技术来测量电子的温度和数密度。 本项目通过开发一种称为连续波激光汤姆逊散射（CW LTS）的诊断方法来解决这一需求，以定量测量电子。 使用CW LTS，高功率激光束照射待研究的等离子体，激光光子被等离子体电子弹性散射（就像碰撞的台球）。 然后检测散射的光子，从而可以推断等离子体的电子性质。 该项目将有利于低温等离子体的基础研究以及技术应用，包括半导体工业的等离子体处理，空间探索的等离子体推进器和大气压等离子体。该项目还旨在吸引来自代表性不足群体的学生参加CO2激光演示的开发，以推广到当地K-12学生。该项目旨在开发一种新的激光汤姆逊散射（LTS）模式，该模式基于使用连续波（CW）、高功率（kW）光源，与使用脉冲激光的传统系统相比，可以实现更高的散射计数和更高的检测限。 由于信号流是连续的，CW LTS方法将尝试将LTS从测量时间平均电子参数推进到捕获高达~10-100 kHz的时间分辨动态。 这将代表LTS对研究等离子体动力学的前所未有的强大进步，例如脉冲放电中的电离和复合，等离子体波和霍尔效应推进器中的呼吸模式等振荡。诊断方面的进展将在出版物和会议上分享，并将纳入科罗拉多州立大学的本科和研究生课程。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will aim to develop a novel diagnostic to quantitatively study electron populations in a low temperature plasma. Plasma, often referred to as the fourth-state of matter, is a gas that contains charged species such as electrons and ions. Low temperature plasmas that also contain energetic atoms and molecules, referred to as radicals, can enable many technological applications. The properties of low temperature plasmas are largely governed by electrons and an ongoing challenge in plasma science has been to develop diagnostic techniques to measure the temperature and number density of electrons. The present project addresses this need through the development of a diagnostic, referred to as continuous-wave Laser Thomson scattering (CW LTS), to quantitatively measure the electrons. With CW LTS, a high-power laser beam illuminates the plasma to be studied and the laser light photons are elastically scattered by the plasma electrons (like colliding billiard balls). The scattered photons are then detected allowing one to infer electron properties of the plasma. The project will benefit basic investigations of low temperature plasmas as well as technological applications including processing plasmas for the semiconductor industry, plasma thrusters for space exploration, and atmospheric pressure plasmas. The project will also aim to attract students from underrepresented groups to participate in the development of a CO2 laser demonstration for outreach to local K-12 students. The project seeks to develop a new paradigm for Laser Thomson scattering (LTS) based on using continuous-wave (CW), high-power (kW) light sources to achieve higher scattering counts and improved detection limits as compared to conventional systems with pulsed lasers. Since the signal stream is continuous, the CW LTS approach will attempt to advance LTS from measuring time-average electron parameters to capturing temporally resolved dynamics up to ~10-100 kHz. This would represent an unprecedented and powerful advance of LTS towards studying plasma dynamics such as ionization and recombination in pulsed discharges, plasma waves, and oscillations such as the breathing mode in Hall effect thrusters. The diagnostic advances will be shared in publications and conferences and will be integrated into undergraduate and graduate courses at Colorado State University. Students from underrepresented minority groups will be sought to work on the project both for graduate thesis research and for undergraduate research experience.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.