Real-time monitoring system for plasma density in long pipeline and application method of real-time monitoring system

The invention discloses a long pipeline internal plasma density real-time monitoring system and an application method thereof, and aims to solve the problem that the plasma density is difficult to detect when the interior of an existing long pipeline is coated. According to the real-time monitoring system for the plasma density in the long pipeline, supports are arranged on the left side and the right side of a table top of a damping platform, three movable frames are slidably connected to a guide rail, a long-focal-length lens, a short-focal-length lens and a spectrum probe are arranged on the three movable frames correspondingly, and a fixed support is fixedly connected to the guide rail; the telescopic darkroom is arranged on the fixing support, the long-focal-length lens, the short-focal-length lens and the probe are located in the telescopic darkroom, the open end of the telescopic darkroom is in butt joint with the film coating pipeline, the other end of the telescopic darkroom is closed, and the probe