In situ soft X-ray absorption spectroscopy of flames

Understanding the ignition mechanism of high-pressure spray flames

“…In order to capitalize on powerful X-ray absorption techniques, a few attempts have been made to implement such techniques in situ in flames. Figure 11b shows an example of a NEXAFS spectrum taken in a non-sooting low-pressure methane jet flame [281]. The largest peaks observed are attributable to the gas-phase species CO, CO 2 , and CH 4 , which are shown individually in Fig.…”

Characterization of scalar mixing in dense gaseous jets using X-ray computed tomography

“…In contrast, soft X-rays from low-energy coherent synchrotron radiation represent a more typical source for X-ray measurements of gas-phase phenomena (Frank et al 2014). The work of Kastengren and Powell (2014) highlights the potential advantages of synchrotron sources over laboratory-scale X-ray sources in providing bright, monochromatic beams.…”

In situ temperature measurements in sooting methane/air flames using synchrotron x-ray fluorescence of seeded krypton atoms

“…The challenge is that the material density in flames is orders of magnitude lower than in solids, especially because the temperature can exceed 2000 K. However, these measurements are becoming feasible because of the greater availability of synchrotron x-ray sources with high brilliance (3) and improvements in x-ray optics, such as Kumakhov lenses, which can efficiently collect emitted or scattered x-rays over an extended solid angle (4). Several recent studies have used XRTs to measure temperature or species concentrations in flames (5)(6)(7)(8)(9)(10). For example, x-ray computed tomography has been used to image premixed methane/air flames composed of 25 to 65% krypton by mole fraction, and temperatures were obtained from x-ray attenuation measurements (10).…”