Design and optimization of hydrogen cooled pulsed storage inductors for electromagnetic launchers

Experimental results are reported on hydrogen-cooled aluminum cryoresistive coils operating at frequencies greater than 1 Hz. It is shown that eddy current losses due to pulsing are minimized by using single-layer coils. Higher losses of cabled conductors and multilayer coils are caused by self-shielding of each conductor or layer from the AC fields from the other conductors. I²R losses for cable is low if the wire size is much smaller than the skin depth (d<<2 mm). High-purity aluminum inductors pulsed at 1 Hz for a few minutes have storage efficiencies greater than 95%. High-modulus-low-density structural materials are required to limit conductor strain and resistivity degradation. Optimization of energy stored per unit mass is discussed, and conceptual designs of 300-MJ hydrogen cooled cryoresistive toroids and solenoids are examined