首页>
外文学位
>The Gravity Probe B niobium bird experiment: Experimental verification of a data reduction scheme with a prototypical dc SQUID readout system.
【24h】
The Gravity Probe B niobium bird experiment: Experimental verification of a data reduction scheme with a prototypical dc SQUID readout system.
This dissertation describes the concept and the latest results from the niobium bird experiment, which is an integrated, end-to-end test environment for the data reduction scheme and the readout system designed for the Gravity Probe B program (GP-B).; The Gravity Probe B program is a relativity gyroscope experiment begun at Stanford University in 1960 and supported by NASA since 1963. This experiment, for the first time, will check the relativistic precession of an Earth-orbiting gyroscope that was predicted by Einstein's General Theory of Relativity, to an accuracy of 1 milliarcsecond per year or better. A drag-free satellite will carry four gyroscopes in a polar orbit to observe their relativistic precession. The primary sensor for measuring the direction of the gyroscope spin axis is the SQUID (superconducting quantum interference device) magnetometer. The data reduction scheme designed for the GP-B program processes the signal from the SQUID magnetometer and estimates the relativistic precession rates. I reformulated the two-step Kalman filters, originally developed by J. V. Breakwell and X. Qin, and designed the niobium bird experiment to verify the performance of the data reduction scheme experimentally with SQUID readout hardware within the test loop.; The niobium bird experiment comprised three major components: a truth model, Kalman filters, and a SQUID readout system. The truth model simulated the science signal, which was injected into the SQUID readout system. The SQUID output was then fed into the two-step Kalman filters as a measurement, and the true values and the estimates by the filters were compared to evaluate the filter performance.; The latest results from the niobium bird experiment showed that the temperature-dependent bias drift in a commercially available dc SQUID was about twenty times larger than what I assumed in the simulation and was too large to achieve the required estimation accuracy. For the GP-B science mission, the bias drift in the SQUID readout can be reduced to meet the requirement by implementing a temperature regulation system and designing a SQUID controller with a smaller temperature coefficient.
展开▼
机译:本文介绍了铌鸟实验的概念和最新结果,该实验是一个针对数据缩减方案和为重力探针B程序(GP-B)设计的读出系统的集成的,端到端的测试环境。重力探测器B计划是一个相对论陀螺仪实验,于1960年在斯坦福大学开始,自1963年以来一直得到美国国家航空航天局(NASA)的支持。该实验将首次检验爱因斯坦的通用地球理论所预测的绕地球旋转的陀螺仪的相对论进动。相对性,每年的精度为1毫秒或更高。一个无阻力的卫星将在极地轨道上携带四个陀螺仪,以观察它们的相对论进动。用于测量陀螺仪旋转轴方向的主要传感器是SQUID(超导量子干涉仪)磁力计。为GP-B程序设计的数据缩减方案处理来自SQUID磁力计的信号,并估计相对论进动率。我重新制定了最初由J. V. Breakwell和X. Qin开发的两步卡尔曼滤波器,并设计了铌鸟实验,以在测试环路内使用SQUID读出硬件来实验性地验证数据缩减方案的性能。铌鸟实验包括三个主要部分:真值模型,卡尔曼滤波器和SQUID读出系统。真值模型模拟了科学信号,该信号被注入到SQUID读数系统中。然后将SQUID输出作为测量结果馈入两步卡尔曼滤波器,并比较滤波器的真实值和估计值以评估滤波器性能。铌鸟实验的最新结果表明,市售直流SQUID中与温度有关的偏置漂移比我在模拟中假设的要大二十倍左右,并且太大而无法达到所需的估计精度。对于GP-B科学任务,可以通过实施温度调节系统并设计具有较小温度系数的SQUID控制器来减少SQUID读数中的偏差漂移以满足要求。
展开▼