Online vacuum degree detection system and method based on single-fiber laser-induced breakdown spectroscopy

An online vacuum degree detection system based on single-fiber laser-induced breakdown spectroscopy, comprising:

• a laser device, which generates laser that excites the laser through fiber induced breakdown spectroscopy, wherein the laser generated by the laser device has an energy of the laser 1 is 24 mJ, and has a wavelength of 1,064 nm;
• a fiber coupler, which couples and injects the laser;
• a single fiber, which is connected to the fiber coupler to transmit the laser, wherein a central glass core of the single fiber has a core diameter of 400 μm-600 μm;
• a material of a core layer of the single fiber adopts GeO2 or SiO2;
• and a material of a cladding layer of the single fiber adopts SiO2;
• a laser-induced breakdown spectroscopy (LIBS) probe, one end of which is connected to the single fiber, and the other end of which extends into a vacuum arc-extinguishing chamber, wherein the laser is conducted by the fiber and is induced by the LIBS probe to generate plasma, and the plasma is subjected to self-emission imaging and enters the fiber coupler via the LIBS probe, and the LIBS probe is a single-lens-based LIBS laser probe;
• during focusing, laser spots are focused and emitted through a lens to a shield target material of an arc-extinguishing chamber in a vacuum switch to generate the plasma;
• a dichroscope, which is arranged on the fiber coupler to separate the laser from the plasma;
• an achromatic instrument, which is connected to the fiber coupler;
• a collection fiber, which is connected to the achromatic instrument to collect the plasma via the achromatic instrument;
• a spectrometer, which is connected to the collection fiber to generate a spectral signal;
• an intensified charged couple device (ICCD)-camera, which is connected to the spectrometer to collect a plasma image and further is used for taking pictures, wherein a filter is placed in front of the camera to filter plasma radiation and background noise to obtain a plasma image;
• and analysis is performed to obtain a vacuum degree;
• a digital delay pulse generator, which is connected to the ICCD camera to control the ICCD camera by means of setting a delay between pulses and is configured to trigger the laser and the ICCD camera, wherein a time interval is adjusted to track evolution of the plasma;
• a plasma imaging system, comprising the lens and being configured for achieving a focusing effect in the single-fiber, LIBS probe and the dichroscope for separating plasma emission from a laser path;
• and
• a processor, which is connected to the ICCD camera and the spectrometer, wherein a plasma temperature and a plasma density are generated based on the plasma image and the spectral signal, so as to obtain thea vacuum degree;
• wherein
• the laser is injected into the single fiber for transmission by the fiber coupler and transmitted to the LIBS probe to excite and induce a shield target material of the vacuum arc-extinguishing chamber;
• the fiber coupler reflects a main laser beam through the dichroscope and injects the reflected main laser beam into the transmission fiber;
• the plasma is subjected to self-emission imaging and enters the fiber coupler via the LIBS probe;
• the dichroscope separates the laser from the plasma and the collection fiber collects the plasma via the achromatic instrument;
• an output of the laser is focused by using an imaging principle;
• a laser spot on a fiber end face of the single fiber is imaged and mapped to a target surface through an aspherical lens to generate the plasma;
• self-emission of the plasma is also imaged to an output end face of the fiber laser device and the plasma is then transmitted back through the single fiber;
• emission of the plasma is separated from the laser path via the dichroscope;
• the plasma is guided by the achromatic instrument to be emitted into the collection fiber which is connected to the spectrometer;
• the digital delay pulse generator is used to trigger a laser source and the ICCD camera;
• the ICCD camera is used to acquire an image of the plasma;
• a spectral signal result is analyzed to obtain a vacuum measurement numerical value, thus achieving online monitoring of a remote vacuum switch equipment;
• and
• the laser starts from the laser device to the fiber coupler, the single fiber and single-fiber LIBS probe.