# Study on Electromagnetic Radiation Interference Caused by Rocket Fuel
## 2 Methods
### Data Processing Method  
Electromagnetic radiation propagates from a radiation source to space through a certain medium in the form of electromagnetic waves, while the mechanism of electromagnetic radiation around a spacecraft is embodied in the influence and threat of the radiation. The electromagnetic environment around a spacecraft is a comprehensive reflection of the complex distribution and changes in the electromagnetic radiation generated by aerospace fuel in terms of space, time, frequency spectrum, and power, which is a direct way of describing the external characteristics of the electromagnetic environment around a spacecraft as its external appearance. This paper analyses and models the electromagnetic environment around a spacecraft through four aspects, the spatial characteristics, time-domain characteristics, frequency-domain characteristics, and energy-domain characteristics, to better evaluate the influence and threat of electromagnetic radiation on electronic equipment in spacecraft. Each electronic device in a spacecraft can be regarded as an electromagnetic sensor, and the electromagnetic interference on every electromagnetic sensor is affected by many parameters, such as the operating time, induction direction, working frequency, working bandwidth, separation distance, and frequency offset. As shown in Figure 3a, these parameters have different effects on the electromagnetic compatibility of the electronic equipment; additionally, the exterior parameters have priority over the interior parameters when calculating electromagnetic interference. That is, the exterior parameters are more important in the process of electromagnetic interference calculation.  
The time-varying power density spectrum \(S(\mathbf{r},t,f)\) is a complicated mathematical expression, which cannot describe the electromagnetic environment simply and intuitively. How to use several indicators to describe the electromagnetic radiation characteristics caused by rocket fuel and build an electromagnetic environment model is a question worth exploring. As shown in Figure 3b, in order to evaluate the electromagnetic environment caused by rocket fuel, in this study the three indicators of space coverage, time occupancy and frequency occupancy were used to describe the characteristics of electromagnetic radiation [21]. The expression of space coverage was as shown in Equation (1), the expression of  
Figure 2: Electromagnetic radiation measurement and analysis process.  
time occupancy was as shown in Equation (2), and the expression of frequency occupancy was as shown in Equation (3). The meaning of the parameters in the equations is shown in Table 1.  
\[\text{SO} =\frac{1}{V_{\Omega}}\int_{\Omega}U\bigg{[}\frac{1}{f_{2}-f_{1}} \frac{1}{t_{2}-t_{1}}\int_{t_{1}}^{t_{2}}\int_{f_{1}}^{f_{2}}S(\mathbf{r},t,f)dft-S_{ 0}\bigg{]}d\tau \tag{1}\] \[\text{TO} =\frac{1}{t_{2}-t_{1}}\int_{t_{1}}^{t_{2}}U\bigg{[}\frac{1}{(f_{2} -f_{1})V_{\Omega}}\int_{\Omega}\int_{f_{1}}^{f_{2}}S(\mathbf{r},t,f)dft-S_{0}\bigg{]}dt\] (2) \[\text{FO} =\frac{1}{f_{2}-f_{1}}\int_{f_{1}}^{f_{2}}U\bigg{[}\frac{1}{(t_{2} -t_{1})V_{\Omega}}\int_{\Omega}\int_{t_{1}}^{t_{2}}S(\mathbf{r},t,f)dtt-S_{0}\bigg{]}df \tag{3}\]