Purpose/Aim
Vacuum switch is a kind of green and pollution-free switching equipment. Its insulation depends on the vacuum degree of the vacuum interrupter, and existing means cannot achieve reliable online monitoring. A vacuum degree detection method based on laser-induced plasma imaging is proposed.
Experimental/Modeling methods
As shown in fig.1, the pulse laser passes through mirror 1, dichromatic mirror 1, dichromatic mirror 2, reflecting mirror 2, focusing lens is focused on the shielding of the vacuum interrupter to induce the plasma. The plasma is imaged on ICCD by focusing lens, reflector 2, dichromatic mirror 2, and imaging lens. ICCD takes plasma images at preset parameters. The integral of plasma radiation intensity is calculated by plasma images, and the vacuum degree is extracted from the relationship between the integral radiation intensity and vacuum degree.
Results/discussion
Fig. 2 is the images of plasma obtained by ICCD at 1 Pa, 10^-1 Pa, 10^-2 Pa, 10^-3 Pa, and the images have been normalized. It can be seen from fig.2 that the radiation intensity of plasma decreases monotonously with increasing air pressure. Fig.3 is the fitting diagram of the radiation intensity integral, the radiation intensity integral fits well with the log10(P) (P is air pressures), and the fitting coefficient R-square reaches 0.99472.
Conclusions
The detection method of vacuum degree of vacuum switch dased on laser-induced plasma imaging can realize vacuum detection, the detection limit is 10^-4 Pa, far lower than the critical failure vacuum degree of vacuum interrupter.
Appendix (Figure, table, image…)
                                
Fig.1. Schematic diagram of the device structure      Fig.2. Pictures of plasma at different pressures   Fig.3. Radiation intensity fitting diagram
 

Vacuum degree detection,Laser induced plasma