A simulation chamber for absorption spectroscopy in planetary atmospheres

A novel simulation chamber, PASSxS (Planetary Atmosphere Simulation System for Spectroscopy), has been developed for absorption measurements performed with a Fourier transform spectrometer (FTS) and, possibly, a cavity ring-down (CRD) spectrometer with a sample temperature ranging from 100 up to 550 K, while the pressure of the gas can be varied from 10 mbar up to 60 bar. These temperature and pressure ranges cover a significant part of the planetary atmospheres in the solar system, and the absorption chamber can thus be used to simulate planetary atmospheres of solar planets and extrasolar planets with similar physical conditions. The optical absorption path for the FTS absorption measurements is 3.2 m due to the implementation of a multi-pass setup inside the chamber. The FTS measurements cover a wide spectral range, from the visible to the mid-infrared, with a sensitivity sufficient for medium-strength absorption bands. The FTS has been used previously to measure high-pressure atmospheres, including collision-induced absorption bands and continuum absorption at ambient temperatures. PASSxS allows the measurement of the temperature dependence of collision-induced bands and continuum absorption, which is important for both the modeling of planetary atmospheres and fundamental processes involving collisions between molecules and atoms.

A simulation chamber for absorption spectroscopy in planetary atmospheres

A novel simulation chamber PASSxS (Planetary Atmosphere Simulation System for Spectroscopy) has been developed for absorption measurements performed with a Fourier Transform Spectrometer (FTS) and, possibly, a cavity ring down (CRD) spectrometer, with a sample temperature ranging from 100 K up to 550 K, while the pressure of the gas can be varied from 10 mbar up to 60 bar. These temperature and pressure ranges cover a significant part of the planetary atmospheres in the solar system and the absorption chamber can thus be used to simulate planetary atmospheres of solar planets and extra solar planets with similar atmospheres. The optical absorption path for the FTS absorption measurements is 3.2 m, due to the implementation of a multipass setup inside the chamber. The FTS measurements cover a wide spectral range, from the visible to the mid-infrared with a sensitivity sufficient for medium strength absorption bands. The FTS has been used previously to measure high pressure atmospheres, including collision induced absorption bands and continuum absorption at ambient temperatures. PASSxS allows to measure the temperature dependence of collision induced bands and continuum absorption, which is important both for the modelling of planetary atmospheres as well as for fundamental processes involving collisions between molecules and atoms.

Numerical investigation into effect of the rubble mound inside perforated caisson breakwaters under random sea states

The paper reports a numerical investigation into the effect of rubble mounds inside perforated caisson breakwaters (PCBs), in which a line-shaped mass source wavemaker is proposed for generating random waves. A series of experiments are employed to validate the numerical model, and good agreements are observed in the comparison of the experimental and numerical results. With the use of the validated numerical model, the numerical investigation is performed, in which the attention is mainly paid to two parameters: the slope angle and porosity of the inner rubble mound. The result shows that, as the slope angle of the inner rubble mound increases, the reflection coefficient is observed to decrease first and then increase, and compared to the experiment, both the positive and negative hydrodynamic pressure acting on the solid rear wall of PCBs is weakened. On the other hand, although a larger inner rubble mound porosity is beneficial to diminish the reflection coefficient, the reduction is not obvious especially when the front wall porosity is small. Furthermore, as the increase of front wall porosity and relative wave absorption chamber length (the ratio of wave absorption chamber length to significant wavelength), the effect of the slope angle and porosity of the inner rubble mound becomes more significant because more waves could enter the wave absorption chamber. The relative wave absorption chamber length considered in the present study ranges from 0.06 to 0.21, and the recommended slope angle is approximately 45 degrees.

Miniaturized photoacoustic detection of organofluorine-based refrigerants

Due to the ban on hydrofluorocarbon and haloalkane refrigerants with a high global warming potential, such as R134a, in the automotive industry, the significance of reliable and precise measuring devices for these refrigerants has risen. We present a photoacoustic gas detector for monitoring the organofluorine-based refrigerants R134a and R1234yf. The idea for this sensor is based on the three-chamber concept (a detection chamber, absorption chamber, and filter chamber). The optimal parameters and dimensions of the photoacoustic sensor components were determined via simulations. The simulation results were the cornerstone of our hardware construction. The first measurements with the newly developed sensor showed a sufficient signal-to-noise ratio for a reliable 0.5 vol. % (0.005 m3 m−3) detection resolution. The influence and importance of the filter chamber were examined and validated.

A Design of Optical Filter Based on Conjugate Interference

In this paper, a conjugate interference filter which could be used in gas sensing is presented .The filter consists of two large spot collimators and a gas etalon which has two separate cells:absorption gas chamber and non-absorption gas chamber. When cascading the broadband light to the filter , only light absorbed by the target gas can pass through the filter and the spectrum of output light matches well with the absorption spectrum of target gas.By changing the target gas in the absorption chamber ,filter for various kind of gases can be implemented. In this paper, acetylene is selected as the target gas and the spectrum of light through the filter completely matches the absorption peak of acetylene after parameter adjustments.