skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br{sub 2} down to 13 μs

Abstract

A chopper wheel construct is used to shorten the duration of a molecular beam to 13 μs. Molecular beams seeded with NO or with Br{sub 2} and an initial pulse width of ≥200 μs were passed through a spinning chopper wheel, which was driven by a brushless DC in vacuo motor at a range of speeds, from 3000 rpm to 80 000 rpm. The resulting duration of the molecular-beam pulses measured at the laser detection volume ranged from 80 μs to 13 μs and was the same for both NO and Br{sub 2}. The duration is consistent with a simple analytical model, and the minimum pulse width measured is limited by the spreading of the beam between the chopper and the detection point as a consequence of the longitudinal velocity distribution of the beam. The setup adopted here effectively eliminates buildup of background gas without the use of a differential pumping stage, and a clean narrow pulse is obtained with low rotational temperature.

Authors:
; ;  [1]
  1. Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Rd, Oxford OX1 3TA (United Kingdom)
Publication Date:
OSTI Identifier:
22392492
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 86; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; BROMINE; DETECTION; LASERS; MOLECULAR BEAMS; MOTORS; NITRIC OXIDE; OPTICAL PUMPING; PULSES; VELOCITY

Citation Formats

Lam, Jessica, Rennick, Christopher J., and Softley, Timothy P. A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br{sub 2} down to 13 μs. United States: N. p., 2015. Web. doi:10.1063/1.4921398.
Lam, Jessica, Rennick, Christopher J., & Softley, Timothy P. A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br{sub 2} down to 13 μs. United States. doi:10.1063/1.4921398.
Lam, Jessica, Rennick, Christopher J., and Softley, Timothy P. Fri . "A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br{sub 2} down to 13 μs". United States. doi:10.1063/1.4921398.
@article{osti_22392492,
title = {A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br{sub 2} down to 13 μs},
author = {Lam, Jessica and Rennick, Christopher J. and Softley, Timothy P.},
abstractNote = {A chopper wheel construct is used to shorten the duration of a molecular beam to 13 μs. Molecular beams seeded with NO or with Br{sub 2} and an initial pulse width of ≥200 μs were passed through a spinning chopper wheel, which was driven by a brushless DC in vacuo motor at a range of speeds, from 3000 rpm to 80 000 rpm. The resulting duration of the molecular-beam pulses measured at the laser detection volume ranged from 80 μs to 13 μs and was the same for both NO and Br{sub 2}. The duration is consistent with a simple analytical model, and the minimum pulse width measured is limited by the spreading of the beam between the chopper and the detection point as a consequence of the longitudinal velocity distribution of the beam. The setup adopted here effectively eliminates buildup of background gas without the use of a differential pumping stage, and a clean narrow pulse is obtained with low rotational temperature.},
doi = {10.1063/1.4921398},
journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 5,
volume = 86,
place = {United States},
year = {2015},
month = {5}
}