Guorong Liu's research while affiliated with Lanzhou University of Technology and other places

... An et al. (2019) reported that the total intensity ratio of the spectra to ionic lines is roughly equal to the diameter ratio of the outer corona envelope to the current-carrying channel core. If the outer corona envelope radius is assumed to be 6 cm (Tausanovic et al., 2017), then the mean channel core radii at the lower end of this tall structure lightning channel at 0.16 and 0.24 ms are estimated as 0.82 and 0.83 cm, respectively, which are consistent with the magnitude of the channel core radius reported in the literature Jayakumar et al., 2006;Wang et al., 2022). ...

... Then, many works aimed to improve the time resolution of the spectrum in order to know the physical parameters' evolution inside the lightning channel. [13][14][15][16][17] In the laboratory, the spectrum of air plasma induced by a laser has something in common with the spectrum of lightning. Because the laser-induced air plasma and lightning are both generated in air at atmospheric pressure, they are pulsed. ...

... Yang et al. [34] analyzed a single sprite produced using a mesoscale convective system (MCS). In addition, the spectra of the lightning were observed [35,36], and its physical parameters, such as the electron temperature, density, and conductivity in the channel, were quantitatively calculated, thus allowing the microphysical information inside and around the channel to be obtained. ...

... 1,2 Normally, the current thermal effect causes a high electron temperature of 20 000-30 000 K, which is the main source of human and animal casualties, forest fires, and electrical system damage. 3,4 The accompanying electromagnetic radiation has a strong burning impact on electronic devices. 5 Many physical parameters in a plasma channel, such as electron temperature (T e ), electron density (n e ), etc., can directly reflect the discharge characteristics of the lightning. ...

... For example, Herschel (1868), Slipher (1917), Orville (1975) studied the lightning emission spectra in the visible band, and Salanave (1961), Warner et al. (2011), Harley et al. (2021) extended the study of emission spectra to near infrared band. Cen et al. (2011), Dong et al. (2017), An et al. (2019), Liu et al. (2019b), An et al. (2021) studied physical characteristics along the lightning discharge path based on emission spectra of lightning. Weidman et al. (1989) recorded the lightning spectra in the near-infrared band of 850-1400 nm, and concluded that the average temperature of the lightning discharge path is approximately 16,000 K. Qu et al. (2012) studied the near-infrared spectra in the range of 760-970 nm and calculated that the temperature of the three lightning discharge paths are all about 16,000 K. Zhang et al. (2013) analyzed the radiation characteristics of lightning plasma in the visible and infrared bands, and calculated that the temperature of the lightning discharge path can reach more than 30,000 K. Mu et al. (2016) found that the temperature decay of the lightning discharge path is slower than the current change and that the temperature of the lightning discharge path remains at about 20,000 K up to 200-400 μs after the peak current by using the time-resolved spectra of the lightning return stroke process. ...

... Spectral observations can record the emission spectrum of the lightning channel and can be used to retrieve physical information from inside the channel. Lightning spectral measurements with high spatial and temporal resolution have been used to reveal the details of lightning channels (Zhang et al., , 2020bWang et al., 2019cWang et al., , 2021dWang et al., , 2022bLiu et al., 2019aLiu et al., , b, 2021dLiu et al., , 2022Wan et al., 2021;Chen et al., 2022b). Zhang et al. (2019a) investigated the variation characteristics of return stroke current along the discharge channel, and three types of variation trends with height were found. ...

... Lightning spectral measurements with high spatial and temporal resolution have been used to reveal the details of lightning channels (Zhang et al., , 2020bWang et al., 2019cWang et al., , 2021dWang et al., , 2022bLiu et al., 2019aLiu et al., , b, 2021dLiu et al., , 2022Wan et al., 2021;Chen et al., 2022b). Zhang et al. (2019a) investigated the variation characteristics of return stroke current along the discharge channel, and three types of variation trends with height were found. The attenuation factor is roughly positively correlated with the intensity of discharge. ...

... Uman has confirmed that lightning channels meet the LTE [21]. Under these two conditions, the temperature of the channel can be calculated by the Boltzmann plot method from the following relationship [16,22]: ...

... However, it is uncertain how well a laser can mimic lightning chemistry. In a natural lightning channel, gas is heated within a few microseconds to a peak temperature of 30 000 K. 29,30 The gas cools to ∼ 3000 K over a few to tens of milliseconds. 31,32 While the gas is cooling NO forms. ...

... Since the value of the plasma frequency depends on the density n of unbound electrons in the plasma membrane, the lucky observation becomes even more interesting. A subsequent paper of the same group [43] estimated the maximal luminous intensity of visible light to be 4.2 kW. Usually, the luminosity of BL is comparable to that of an electrical light bulb (50 -100 W). ...