Several types of multi-stage flux-trapping helical flux compression generators for high impedance loads are considered. Short-pulse two-stage helical generators with diameter 100 mm and initial energy of 0.5-3 kJ have supplied energy up to 40 kJ into a 5-/spl mu/H inductive load in a time of about 15 /spl mu/s. Long-pulse two-stage generators with final helix diameter of 110 mm initial energy of 0.8-2.7 kJ have supplied energy up to 350 kJ into a 0.3-/spl mu/H inductive load. Long-pulse three-stage generators with final helix diameter of 160 mm and initial energy of approximately 5 kJ have supplied up to 700 kJ into a 0.5-/spl mu/H inductive load. Model generators without flux trapping and with final helix diameter of 160 mm and initial energy of approximately 20 kJ have supplied energy up to 1.0 MJ into a 0.5 /spl mu/H inductive load. Long-pulse two-stage generators with final helix diameter of 160 mm and initial energy of approximately 30 kJ produce energy up to 1.6 MJ in a load of 0.5 /spl mu/H.