Energy deposition of superpinched relativistic electron beams in aluminum targets

Abstract

Dynamic response data, which traditionally have been used to obtain equation‐of‐state (EOS) information of materials, were instead used here to study energy deposition of an intense (∼10¹¹ W/cm²) tightly focused relativistic electron beam (REB). Measurements of the REB‐induced shock‐wave transit time and average rear‐surface velocity were compared with two‐dimensional hydrodynamic calculations which contain well‐known EOS information for 6061‐T6 aluminum. The experimental results were consistent with classical electron deposition, i.e., a one‐dimensional Monte Carlo transport calculation. In addition, peak pressures in the range 1–2 Mbar (0.1–0.2 TPa) were implied. Two anomalous effects were observed: (i) a low‐amplitude (free‐surface velocity ∼10⁴ cm/sec) precursor signal, preceding the REB‐induced shock wave and (ii) a velocity distribution of material behind the rear surface of the target following the arrival of the REB‐induced shock wave.