Experimental study of a cryogenic pneumatic thrower for launching soft projectiles in avalanche protection

A novel cryogenic pneumatic launcher for remote avalanche initiation has been developed and experimentally investigated. The system uses liquid nitrogen as a working medium, with its explosive evaporation triggered by the heat of a thermite reaction. The rapid phase transition of the cryofluid generates high pressure without sharp shock waves and enables smooth acceleration of soft-bodied projectiles without structural damage. This approach eliminates key drawbacks of conventional avalanche control methods, such as artillery and gas-dynamic Avalauncher systems. A laboratory-scale prototype was built (a 4-meter-long steel barrel with an outer diameter of 89 mm) equipped with an optical chronograph to measure projectile velocity (~ 1 kg). The internal ballistics were studied for thermite charges of 3-6 g and liquid nitrogen volumes of 0-200 ml. It was found that with 3 g of thermite, the optimal performance was achieved by adding ~ 100 ml of liquid N₂, resulting in a projectile speed of ~ 55 m/s, maintained up to barrel exit. Increasing the charge to 6 g of thermite and 200 ml of liquid N₂ raised the peak velocity to over 90 m/s and extended the acceleration phase. The results confirm the feasibility and advantages of the proposed. Method projectiles accelerate without damage, and the system ensures high mobility, environmental safety (no fragments), and a controlled pressure profile with sufficient delivery range. The combination of gentle acceleration and operational mobility makes the launcher promising for avalanche control and other applications.