Fig. 1. Layout and basic parameters of the ALT-3 device (projected). 1 and 2: Ø0.4 m helical and 15-module disk explosive magnetic generators (HEMGs and DEMGs); 3 and 4: explosive closing switches (ECS)—crowbar 3 disconnects the HEMG at initial DEMG current I₀ = 7 MA (t = t₀); ECS 4, having low resistivity R_kl, connects a load of inductance L₀ = 6 nH at a given time t_0l, at fuse opening switch (FOS) voltage U_0l < 10 kV; 5: electrically exploded FOS with Cu foil of thickness Δ_f = 0.12–15 mm and height ∼90 cm; 6 and 7: coaxial-radial transmission line (TL); 8: ponderomotive unit (PU) with an Al liner of outer and inner radius R_l = 4 cm and R_in0 = 3.7 cm (Δ_Al = 3 mm) and height H_l ∼ 1.2R_l; 9: PU end walls; 10 and 11: current probes; 12: measuring unit of radius R_imp = 1 cm (implosion depth R_in0/R_imp = 3.7) with photon doppler velocimetry (PDV) probes and test samples.

Fig. 2. (a) Load current derivative dI/dt in the ALT-2 experiment and in the previous simulation (heavy and fine lines, dashed line represents the calculated FOS voltage U_f); (b) dI/dt and inner liner surface velocity v_in(t) in the revised and previous simulations (heavy and fine lines).

Fig. 3. Results of revised simulation of the ALT-3 device (heavy lines), previous simulation (fine lines), and simulation 1 (dashed line): (a) currents I_g(t) and I(t) and inductance L(t) in the load; (b) current derivative dI/dt and velocity of the inner liner surface v_in(t); (c) FOS voltage U_f(t) and rate of magnetic flux losses in the load U₋(t); (d) profiles of ramp P(r) and magnetic P_B(r) pressures in the liner at the end of implosion (R_in = R_imp = 1 cm).

Fig. 4. Results of device simulations with Cu/W and Cu liners (6) at FOS Cu foil thickness of 0.15 mm [nos. 6(4w), 8(4cu), and 10(4w₀) in Table I]. (a) Currents in DEMG I_g(t) and liner I(t), load inductance L(t); (b) voltages on foil U_f(t) and load walls U₋(t); (c) pressure P_ex(t) on the outer boundary R_ex(t) of the tested liner layer and velocity v_in(t) of the inner boundary R_in(t) of this layer; (d) profiles of ramp P(r) and magnetic P_B(r) pressures in the liner at the end of implosion (R_in = R_imp = 0.7 mm).

Fig. 5. (P_ex vs R_ex) and (v_in vs R_in) plots of the outer and inner boundaries of the liner’s tested W layer from simulations 6(4w) and 10(4w₀), see Table I and Fig. 4.

Table 1. Results of simulations of devices with Al/W and Al/Cu liners (3), R_in0/R_imp ∼ 27 (simulations 1–4) and simulations of devices with Cu/W and Cu liners (6), R_imp = R_in0/R_imp = 18–26 (simulations 5–10). Here, Δ_f and U_0l are the Cu foil thickness and voltage at t = t_0l (Fig. 1); I_g, U_f1 − U_f2, and U₋ are the maximum values of DEMG current and voltage on FOS (peaks 1 and 2) and load walls; I and L are the maximum current and respective load inductance; B and P_B are the highest magnetic field and magnetic pressure in the liner’s skin layer; P_ex, P_max, and v_max are the pressures on the outer surface and inside the layer, and layer velocity at the end of implosion (R_in = R_imp).