# Mechanism Study of Combustion Dynamics of GO@CL-20 Composite
## 2 Materials and Methods
### Experiment Methods
#### 2.2.2 High-Temperature Cracking Experiment  
The shock tube was constructed from 304 stainless steel, featuring a driver section measuring 3.05 m in length and a driven section measuring 1.5 m in length, both with an internal diameter of 44 mm. The critical component, the dump chute, is attached to the low-pressure section of the shock tube via a baffle valve, also with an internal diameter of 44 mm. This valve serves to prevent the formation of multiple reflected shock waves within the shock tube during experiments, ensuring that the shock wave propagates as a single pulse. As illustrated in Figure 2, five pressure sensors were installed on the side wall of the low-pressure section near the end cap to monitor the pressure rise at various time points. By measuring the distance between these sensors, the velocity of the incident shock wave was determined. The analysis and calculation of the shock wave's speed were performed using the widely recognized Gaseq 0.7 software, developed by Professor [PERSON] of Columbia University [23; 24; 25; 26]. This software includes a module for reflected shock, which calculates the state of the low-pressure region after the shock wave reflects from the shock tube, providing data on the temperature and pressure of the low-pressure region post-reflection.  
Prior to conducting any experiments, 100 mg of energetic material powder was weighed using an electronic analytical balance and evenly spread onto a thin blade. Subsequently, the blade was mounted on the adjusted support rod and positioned within the low-pressure chamber of the shock tube. The high-pressure chamber and low-pressure chamber were evacuated using a mechanical pump and a turbomolecular pump, respectively. Once the low-pressure chamber has been evacuated to an ultimate vacuum of \(3\times 10^{-2}\) Pa by the turbomolecular pump, the diluted gas is filled to the predetermined pressure. To prevent the energetic material powder from rising prematurely from the blade before breaking the film, it is necessary to control the rate of vacuuming while vacuuming the low-pressure chamber. The experiment demonstrated that if the pressure in the low-pressure chamber decreased at a rate of 1 kPa/s, the energetic material powder would remain on the blade after vacuuming [27; 28; 29].  
Figure 2: Schematic diagram of single-pulse shock tube structure.  
The outer wall of the shock tube is wrapped with heating tape and insulation material. When N\({}_{2}\) is used as a diluting gas, it is sufficient to maintain the entire experimental system at room temperature (25 \({}^{\circ}\)C). Once the low-pressure chamber is filled with gas, it is then filled into the high-pressure chamber and the middle section. The film-breaking experiment is then conducted once the pressure reaches the specified level. At the moment of film breaking, the high-pressure gas exerts a force on the low-pressure gas, resulting in the generation of a shock wave. As the shock wave passes through the blade, it raises and disperses the energetic material powder on the blade. The tail cap reflects the shock wave, which then passes through the energetic material powder, heating it to the expected temperature.  
The specific gas chromatography model used in this paper is Agilent GC7820A in Shanghai, China. The Agilent GC7820A gas chromatograph is straightforward to operate and offers dependable analytical outcomes, rendering an optimal choice for routine analysis. The system is equipped with EZChrom Elite 3.2.0 software, which enables the user to modify the operational parameters of the gas chromatograph and display the status of the chromatograph [30; 31]. The chromatograph is equipped with a hydrogen flame ionization detector (FID) and a thermal conductivity detector (TCD).