Ultra-Fast Acceleration of Macroscopic Objects in Coaxial Electromagnetic Launcher

Summary form only given. In the paper we present experimental results on launcher of steel projectiles of 15 length caliber in a coaxial electromagnetic launcher. An ultra-fast acceleration of lengthy projectiles in ordinary rail electromagnetic accelerators is associated with definite technical troubles. Currents with a linear density of 10
⁸
A/m should be passed on the rails at acceleration rate of 10 m/s
²
. This leads to a surface explosion. Besides, a magnetic pressure effects not only the projectile, but also the whole design of the launcher destroying the current carrying bars.In the considered launcher the current linear density does not exceed 2.4-10
⁷
A/m. Due to axial symmetry of the construction deformation, a magnetic field pressure is not high. However, a linear inductance of a coaxial is smaller, and high currents are necessary for acceleration. In our experiments powering of the launcher with a bore length of 30 cm was provided from a high-voltage capacitor bank of 900-1350 muF capacity at a voltage of 25 kV. Matching of the low impedance launcher with the high-voltage battery was carried out with step-down cable transformers with transformation coefficients of 28 and 15 depending on the experiment edition. Acceleration of the projectiles of square section of 4x4 mm, length of 60 mm made of stainless steel 12X18H10T of 7.5 g was studied. At full current of the launcher of 1.5 MA and 2.4 MA the projectile velocity was 0.7 km/s and 1.3 km/s, acceleration rate was 5-10
⁶
m/s" and 10' m/s
²
, correspondingly.