RUI: Optical Charge Mitigation Studies with the Trinity University Kelvin Probe

该奖项支持Trinity大学继续开展一项研究计划，以研究LIGO及其后继者中与静电充电相关的问题。该实验室基于真空兼容的开尔文探针，对每平方厘米不到10，000个电子敏感。以前，这种设置已被用于测量熔融石英光学器件的相关时间，演示通过紫外线（UV）照明放电，并测量放电率作为照明波长的函数。该奖项将允许额外的测量，包括对LIGO类光学器件上电荷的空间变化的研究，测量紫外线照明控制的程度？贴片效应？（升高电荷的隔离区域），检查当光学器件交替地暴露于正离子化气体和自由电子时的放电速率和产生的空间变化，以及调查导电涂层和不同清洁和处理方法在减少电荷运动的相关时间和控制贴片效应方面的有效性。将使用原子力显微镜和宇宙射线充电模型进行额外的研究。电荷通过干扰光学器件的位置控制、吸引灰尘到光学表面、模仿引力波爆发信号（当被宇宙射线沉积时）以及产生波动电场来为引力波探测器提供噪声。噪声的贡献取决于电荷的大小和电荷运动的相关时间。这些量的合理值表明，充电可能是Advanced LIGO的一个限制性噪声源，而与地震停止接触的充电也可能是Enhanced LIGO的限制性噪声源。这项研究为前沿领域的本科生提供了真实的研究体验。

This award supports the continuation of a research program at Trinity University to study issues related to electrostatic charging in LIGO and its successors. The laboratory is based around a vacuum-compatible Kelvin probe sensitive to less than 10,000 electrons per square centimeter. Previously this setup has been used to measure the correlation time for a fused silica optic, to demonstrate discharging through ultraviolet (UV) illumination, and to measure the rate of discharge as a function of illumination wavelength. This award will allow additional measurements including study of the spatial variation of charge on a LIGO-like optic, measuring the extent to which UV illumination controls ?patch effects? (isolated regions of elevated charge), examining the discharging rate and resulting spatial variation when the optic is alternately exposed to a positively ionized gas and free electrons, and surveying the effectiveness of conductive coatings and different cleaning and handling methods in reducing the correlation time for charge motion and controlling patch effects. Additional studies using an atomic force microscope and modeling of charging due to cosmic rays will be conducted. Charge contributes noise to gravitational wave detectors by interfering with the position control of optics, attracting dust to the optical surface, mimicking a gravitational-wave burst signal (when deposited by cosmic rays), and generating fluctuating electric fields. The noise contribution depends on the charge magnitude and the correlation time for charge motion. Reasonable values for these quantities suggest that charging may be a limiting noise source for Advanced LIGO, and charging from contact with earthquake stops could be limiting for Enhanced LIGO as well. This research at provides a real-word research experience to undergraduates in a cutting-edge field.