Large-area imager of hydrogen leaks in fuel cells using laser-induced breakdown spectroscopy

Abstract

We constructed a simple device, which utilized laser-induced breakdown spectroscopy to image H2 gas leaking from the surfaces of hydrogen fuel cells to ambient air. Nanosecond laser pulses of wavelength lambda=532 nm emitted from a neodymium-doped yttrium aluminum garnet laser were first compressed to a pulse length Deltat<1 ns using a stimulated Brillouin backscattering cell. Relay-imaging optics then focused this beam onto the H(2) leak and initiated the breakdown plasma. The Balmer-alpha (H-alpha) emission that emerged from this was collected with a 2-m-long macrolens assembly with a 90-mm-diameter image area, which covered a solid angle of approximately 1 x 10(-3)pi steradians seen from the plasma. The H-alpha light was isolated by two 100-mm-diameter interference filters with a 2 nm bandpass, and imaged by a thermoelectrically cooled charge-coupled device camera. By scanning the position of the laser focus, the spatial distribution of H2 gas over a 90-mm-diameter area was photographed with a spatial resolution of < or = 5 mm. Photoionization of the water vapor in the air caused a strong H-alpha background. By using pure N2 as a buffer gas, H2 leaks with rates of <1 cc/min were imaged. We also studied the possibilities of detecting He, Ne, or Xe gas leaks.

Analysis of Pharmaceutical Tablet Coating Uniformity by Laser-Induced Breakdown Spectroscopy (LIBS)

“…This study demonstrates the use of laserinduced breakdown spectroscopy (LIBS) [15], a spectroscopic technique to investigate the sources of variability in coating uniformity in tablets and which attempts to establish statistical significance, or lack thereof, of the possible causes. The LIBS technique finds application in a wide variety of areas such as the study of soil composition [16], polymers [17], minerals [18], metallic compounds [19,20], cosmetics [21], gaseous mixtures [22], construction materials [23], hazardous material detection [24], and traditional fuels such as coal [25], fuel cells [26], and biological tissues [27,28]. The pharmaceutical industry is beginning to consider this technique for in-line monitoring and product analysis applications.…”

Development of narrowband lasers for spectroscopy of antiprotonic atoms

“…These lasers can also be used to carry out studied of the atomic cascades and state lifetimes of pHe + [21][22][23], and laser spectroscopy of Rydberg pHe 2+ ions [24], which are two-body systems composed of a helium nucleus and an antiproton. Some of the lasers described here were also used to spatially detect hydrogen gas leaking from chambers [25].…”

Progress in precise laser spectroscopy of antiprotonic helium atomsThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.

“…The linewidth of the pulsed laser beam was typically around G *60 MHz [9]. The pulsed Nd:YAG lasers used here were also utilized recently to detect hydrogen gas leaks [22] from fuel cells.…”