Plasma jet device

The invention relates to a plasma jet device comprising a shell. A waveguide and an inner conduit are installed in the shell. One end of the waveguide is connected with a microwave power supply. A cavity is arranged between the inner conduit and the waveguide. The cavity is provided with an air inlet which can be closed and opened. The shell is provided with a nozzle which is conducted with the inner conduit. A telescopic metal sheet is arranged at the nozzle. The metal sheet is in contact with a temperature sensor. The temperature sensor is connected with a controller. The controller is alsoconnected with the power supply and an alarm respectively. Compared with the devices in the prior art, the size of the plasma jet is positively relate to the output power of the power supply, the telescopic metal sheet, the temperature sensor and the controller are arranged and the plasma jet flux can be calculated and the output power of the power supply can be automatically adjusted so that thepurpose of autonomously ad