Design and Characterization of Compact Discharge Units for Advanced LIGO

高级激光干涉引力波天文台（LIGO）成功的剩余风险之一是由于干涉仪中用作测试质量的镜子上的电荷积累而产生的过量噪声。该奖项资助的研究将导致紧凑型放电单元（CDU）的建设，可用于减轻测试质量的电荷。每个单元都有一个可操纵的低能电子束来中和正电荷，还有一个广角紫外线束来光喷射负电荷。CDU的尺寸、可靠性和放电电流将在Advanced LIGO测试质量的光学涂层可容忍的紫外辐射水平内进行优化。这些装置的测试将使用现有的扭转天平进行，该天平可以测量带有导电表面的绝缘体上的绝对电荷。事实上，电荷减轻对于各种精密机械实验都很重要，包括先进LIGO、扭转天平和卫星惯性质量。在所有这些系统中，敏感的测试质量与其周围环境电隔离。电荷积累会导致测试质量和附近表面之间的虚假耦合。这种不必要的耦合导致过多的噪声，降低了实验的性能。紧凑型放电单元可用于通过中和测试质量上的电荷来减少这种外来噪声。研究生将参与该项目。

One of the remaining risks for the success of the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) is excess noise due to charge accumulation on the mirrors used as test masses in the interferometer. Research funded by this award will lead to the construction of compact discharge units (CDUs) that can be used to mitigate the charge on the test masses. Each unit features a steerable, low-energy electron beam to neutralize positive charges and a wide angle UV beam to photo-eject negative charges. The CDUs will be optimized for size, reliability, and discharge current within the UV-radiation level tolerable for the optical coating of the Advanced LIGO test masses. Testing of the units will be performed with an existing torsion balance that can measure the absolute charge on an insulator with conducting surface.In fact, charge mitigation is important for a variety of precision mechanical experiments, including Advanced LIGO, torsion balances, and inertial masses in satellites. In all these systems, a sensitive test mass is electrically isolated from its surroundings. Charge accumulation can lead to spurious coupling between a test mass and nearby surfaces. This unwanted coupling leads to excess noise, degrading the performance of the experiments. The compact discharge unit can be used to reduce this extraneous noise by neutralizing charge on the test mass. Graduate students will participate in this project.