An Introduction to Space Instrumentation,
Edited by K. Oyama and C. Z. Cheng, pp. 47-51.
© TERRAPUB, 2013.

Wind measurements: Trimethyl aluminum (TMA) chemical release technique

M. F. Larsen

Deparment of Physics and Astronomy, Clemson University, USA

Abstract: Chemical release techniques have been used since the earliest days of sounding rocket measurements in the upper atmosphere. The measurements require no telemetry or other complicated electronics and the mechanical systems are relatively simple and very robust. The technique was therefore used early on when more complicated measurement techniques were difficult to implement. Chemical release techniques have remained important, however, even as rocket payloads have become more complex. In particular, the tracer measurements remain important as one of the primary techniques for obtaining neutral wind measurements in the upper mesosphere and thermosphere. Various metal vapor tracers have been used for wind measurements in the upper atmosphere, but the most widely used tracer has become trimethyl aluminum (TMA), which has been used in hundreds of rocket launches since the 1960's. The advantages of TMA include the chemiluminescence produced by the tracer, which makes wind measurements possible at any time during the night, and the fact that the tracer is a liquid, which makes it possible to control both the timing and duration of the release more accurately. An overview of the TMA wind measurement technique is presented, including the design of TMA release hardware and recent results from TMA measurements.
Key words: Sounding rockets, thermospheric winds, measurement techniques.

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