## 1 Introduction  
Aerospace pyrotechnic devices usually consist of energetic materials and actuating devices, such as separating nuts, explosive bolts, and cutters. They are used in the connection, unlocking, and separation of parts of spacecraft, such as launch vehicles and satellites, and engine start-up, safety-self-destruction, payload dispersion, and other functional actions of spacecraft [1]. As the primary energetic material in pyrotechnic devices, the ignition composition is ignited by external stimulation (electric energy, laser energy), and then detonates the secondary energetic material. The gas generated by the secondary energetic material drives the actuating devices to complete the predetermined task. The pyrotechnic devices used in deep space exploration missions are exposed to extreme thermal environments, and the maximum operating temperature can reach 130 \({}^{\circ}\)C [2; 3], so the selection of an ignition composition that is insensitive and thermally resistant is crucial [4]. The energetic materials used for ignition can be classified by compounds and mixtures. The ignition performance of compounds is not easy to adjust, among which lead styphnate (LTNR) is most commonly used, and its use temperature should be limited to -40 \({}^{\circ}\)C to 110 \({}^{\circ}\)C [5]. The thermal weight loss ratio of potassium picrate (KP) after exposure to 100 \({}^{\circ}\)C for 48 h is 0.12% [6], and the initial decomposition temperature of potassium styphnate (K\({}_{2}\)TNR) is about 310 \({}^{\circ}\)C [7]. The ignition ability of the mixed ignition composition is strong, which is usually composed of combustible agents (boron, magnesium, aluminum, zirconium, silicon, etc.) and oxidants (potassium nitrate, potassium perchlorate, potassium chlorate, sodium nitrate, polytetrafluoroethylene, etc.). [PERSON] et al. [8] believed that the main thermal weight loss temperature of boron/potassium nitrate (B/KNO\({}_{3}\)) ignition composition was between 545 \({}^{\circ}\)C and 765 \({}^{\circ}\)C, and the thermal stability of the composition at 180 \({}^{\circ}\)C was verified. [PERSON] and [PERSON] [9] found that the critical ignition temperature of aluminum/barium nitrate (Al/Ba(NO\({}_{3}\))\({}_{2}\)), magnesium/ammonium perchlorate (Mg/NH\({}_{4}\)ClO\({}_{4}\)), and magnesium/potassium permanganate (Mg/KMnO\({}_{4}\)) were 599 \({}^{\circ}\)C, 338 \({}^{\circ}\)C, and 289 \({}^{\circ}\)C, respectively. [PERSON] et al. [10] believed that the exothermal peak of aluminum/zirconium/potassium perchlorate (Al/Zr/KClO\({}_{4}\)) ignition composition was around 530 \({}^{\circ}\)C, and the thermal weight loss was concentrated at 400 \({}^{\circ}\)C to 600 \({}^{\circ}\)C.  
The ignition composition of Mg/TeO\({}_{2}\) has the advantages of simple preparation, heat stability, and reliable functioning. The formulation can be adjusted according to the performance requirements of the ignition object, and it meets the requirement of 1A/1W/5 min no-fire (the composition will not be ignited if 1 ampere constant current or 1 watt of electric energy is applied to the composition for 5 min), so the ignition composition of Mg/TeO\({}_{2}\) can be used as primary energetic material of an insensitive igniter [11; 12]. [PERSON] and [PERSON] studied the high-temperature resistance performance of the ignition composition of Mg/Te/TeO\({}_{2}\) (27/67/6), after it was stored at 204 \({}^{\circ}\)C to 240 \({}^{\circ}\)C for 24 h. The ignition current (the average current value that causes the composition to ignite) increased slightly, and storage at 72 \({}^{\circ}\)C and 105 \({}^{\circ}\)C for 2 months had little impact on the ignition time [13]. [PERSON] et al. exposed the ignition composition of Mg/TeO\({}_{2}\) to a high temperature of 165 \({}^{\circ}\)C for 6 days and found that its output peak pressure decreased by less than 5%, the pressure rise time decreased by 8.5%, and the ignition current decreased by 12.8-15.7%.