New laser-based instrument designed to spice up hydrogen analysis

Researchers have developed an analytical instrument that makes use of an ultrafast laser for exact temperature and focus measurements of hydrogen. Their new method might assist advance the research of greener hydrogen-based fuels to be used in spacecraft and airplanes.

“This instrument will provide powerful capabilities to probe dynamical processes such as diffusion, mixing, vitality switch and chemical reactions,” mentioned analysis group chief Alexis Bohlin from Luleå University of Technology in Sweden. “Understanding these processes is fundamental to developing more environmentally friendly propulsion engines.”

In Optics Express, Bohlin and colleagues from Delft University of Technology and Vrije Universiteit Amsterdam, each within the Netherlands, describe their new coherent Raman spectroscopy instrument for finding out hydrogen. It was made potential as a result of a setup that converts broadband mild from a laser with quick (femtosecond) pulses into extraordinarily quick supercontinuum pulses, which comprise a variety of wavelengths.

The researchers demonstrated that this supercontinuum technology could possibly be carried out behind the identical kind of thick optical window discovered on high-pressure chambers used to check a hydrogen-based engine. This is essential as a result of different strategies for producing ultrabroadband excitation do not work when a majority of these optical home windows are current.

“Hydrogen-rich fuel, when made from renewable resources, could have a huge impact on reducing emissions and make a significant contribution to alleviating anthropogenic climate change,” mentioned Bohlin. “Our new method could be used to study these fuels under conditions that closely resemble those in rocket and aerospace engines.”

Getting mild in

There is far curiosity in growing aerospace engines that run on renewable hydrogen-rich fuels. In addition to their sustainability attraction, these fuels have among the many highest achievable particular impulse—a measure of how effectively the chemical response in an engine creates thrust. However, it has been very difficult to make hydrogen-based chemical propulsion techniques dependable. This is as a result of the elevated reactivity of hydrogen-rich fuels considerably adjustments the gasoline combination combustion properties, which will increase the flame temperature and reduces ignition delay occasions. Also, combustion in rocket engines is mostly very difficult to manage due to the extraordinarily excessive pressures and excessive temperatures encountered when touring to space.

“The advancement of technology for sustainable launch and aerospace propulsion systems relies on a coherent interplay between experiments and modeling,” mentioned Bohlin. “However, several challenges still exist in terms of producing reliable quantitative data for validating the models.”

One of the hurdles is that the experiments are normally run in an enclosed space with restricted transmission of optical alerts in-and-out via optical home windows. This window could cause the supercontinuum pulses wanted for coherent Raman spectroscopy to grow to be stretched out as they undergo the glass. To overcome this downside, the researchers developed a option to transmit femtosecond pulsed laser via a thick optical window after which used a course of known as laser induced filamentation to rework it into supercontinuum pulses that stay coherent on the opposite aspect.

Studying a hydrogen flame

To show the brand new instrument, the researchers arrange a femtosecond laser beam with the perfect properties for supercontinuum technology. They then used it to carry out coherent Raman spectroscopy by thrilling hydrogen molecules and measuring their rotational transitions. They had been capable of show sturdy measurements of hydrogen fuel over a variety of temperatures and concentrations and in addition analyzed a hydrogen/air diffusion flame much like what can be seen when a hydrogen-rich fuel is burned.

The researchers at the moment are utilizing their instrument to carry out an in depth evaluation in a turbulent hydrogen flame in hopes of creating new discoveries in regards to the combustion course of. With a purpose of adopting the strategy for analysis and testing of rocket engines, the scientists are exploring the constraints of the method and wish to check it with hydrogen flames in an enclosed barely pressurized housing.