Date of Award

Summer 1964

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering

First Advisor

Horgan, J. D.

Second Advisor

Moeller, Arthur, C.

Abstract

During the late 1950's and early 1960's considerable effort has been devoted to development of instrumentation for earth-orbiting and interplanetary vehicles. One area of substantial interest in this regard has been the measurement of magnetic field strength in these environments. Notable among the experimenters is the group associated with Dr. J. P. Heppner of the NASA Goddard Space Flight Center. Much of the work done by this group has been accomplished with relatively low altitude earth satellites where field strength is of the same order of magnitude as at the terrestial [sic] surface. The instruments used for measurement have employed as a standard the gyromagnetic ratio of various atoms. The rubidium vapor magnetometer produced by Varian Associates of Palo Alto, California is a recent embodiment of this principle, and has been used by Heppner. In view of this stature and contributions in this area of study the rubidium vapor instrument might be considered "the" or certainly "a" state of the art device. This magnetometer, however, exhibits several undesirable characteristics. The first of these is the relatively precise temperature control of the sensor required in order to sustain the optical pumping process with rubidium vapor. The second of these, a characteristic of the self oscillator mode of operation, is the existence of certain orientations with respect to the ambient field in which the instrument does not provide a recoverable output. A parallel development at Texas Instruments Incorporated has been the metastable helium magnetometer which also involves the optical pumping process and the gyromagnetic ratio of helium as a standard. The unlocked oscillator mode of operation of this device lends itself readily to elimination of dead zones by operation with three mutually perpendicular light axes in the sensor. Moreover, the temperature limitations which helium are not as severe as with rubidium vapor. The purpose of the work described herein was to produce an engineering model helium magnetometer to establish its feasibility for use in low altitude earth satellites...

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