Direct detection of momentum flux in atomic and molecular beams
作者:
J. G. Choi,
J. S. Hayden,
M. T. O’Connor,
G. J. Diebold,
期刊:
Journal of Applied Physics
(AIP Available online 1981)
卷期:
Volume 52,
issue 10
页码: 6016-6020
ISSN:0021-8979
年代: 1981
DOI:10.1063/1.329823
出版商: AIP
数据来源: AIP
摘要:
We describe the use of a microphone for detection of atomic and molecular beams in a high‐vacuum environment. Two experiments were carried out to demonstrate this detection method. Pulsed beams of argon were detected using a conventional electret microphone where the output of the microphone was displayed directly on an oscilloscope or processed with a boxcar averager to remove the transient oscillations of the microphone diaphragm. Amplitude modulated, continuous beams of atomic argon were also detected using a lock‐in amplifier. The microphone possesses a response to the pressure or momentum flux in the beam that appears to be unique among beam detectors. We use the classical equipartition theorem to calculate the magnitude of the random fluctuations in the output voltage of the microphone that is used to give an expression for the minimum detectable momentum flux in the beam. For a typical microphone we find this to be 3×10−8Pa, (in a 1‐Hz bandwidth), which corresponds to a minimum number density of 1×106cm−3for an effusive argon beam at 300 K.
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