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

该奖项支持三一大学的一项研究计划的继续进行，该计划旨在研究LIGO及其后续设备中的静电充电相关问题。该实验室的基础是一个真空兼容的开尔文探针，对每平方厘米不到1万个电子敏感。以前，该装置已用于测量熔融石英光学器件的相关时间，以演示通过紫外线（UV）照明放电，并测量放电速率作为照明波长的函数。该合同将允许额外的测量，包括研究类似ligo的光学装置上电荷的空间变化，测量紫外线照明控制的程度。补丁的影响?（电荷升高的孤立区域），检查了当光学器件交替暴露于正电离气体和自由电子时的放电速率和由此产生的空间变化，并调查导电涂层和不同清洁和处理方法在减少电荷运动相关时间和控制斑块效应方面的有效性。将使用原子力显微镜进行进一步的研究，并对宇宙射线产生的电荷进行建模。电荷通过干扰光学器件的位置控制，将尘埃吸引到光学表面，模拟引力波爆发信号（当被宇宙射线沉积时），并产生波动电场，从而对引力波探测器产生噪声。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，电荷可能是高级LIGO的限制噪声源，而与地震停止点接触的电荷也可能是增强LIGO的限制噪声源。这项研究在一个前沿领域为本科生提供了一个真实的研究经验。

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.