In view of the uncertainty in the calibration process of two-color plane laser-induced fluorescence (PLIF) temperature measurement, a new calibration method is proposed, in which the influence of fluorescence yield is considered. The calibration process was carried out at high and low temperature region, respectively. Then, the bias of thermometry results origin from quenching is restrained. This new calibration method is validated in a jet flame with temperature range of 1300–1800 K. Here, the temperature results from Coherent Anti-Stokes Raman scattering (CARS), single-point calibrated PLIF, and two-point calibrated PLIF are all acquired with the maximum standard errors of 13 K, 36 K, and 37 K, respectively. The temperature deviation between the average results from PLIF and Coherent Anti-Stokes Raman scattering (CARS) is 120 K and 10 K, when the two-point and one-point calibration methods are used. Therefore, the two-point calibrated PLIF is preferred in the combustion field, especially with a large temperature range and strong quenching coefficient.

Plasma ignition technology is the research frontier in the field of energy and power. In this paper, a novel type of plasma jet igniter called pre-combustion plasma jet igniter is designed and the experimental results show that it has great potential in strengthening jet stiffness, improving ignition energy, decreasing ignition energy consumption and reducing igniter ablation. The value S called jet stiffness is defined for the first time to reflect the stiffness characteristics of the plasma jet. And the effects of jet gas flow rate, fuel-air ratio and input current on the jet stiffness are investigated experimentally. The experimental results show that the stiffness of the pre-combustion plasma jet is significantly stronger than that of the air plasma jet. When the total jet gas flow rate is increased from 16 L/min to 40 L/min, the stiffness of the air plasma jet and the pre-combustion plasma jet are increased by 73.3 % and 27.2 % respectively. When the current value reaches 30 A, the jet stiffness is increased by about 70 % compared to the input current of 20 A.