High-gain, low-intensity ICF targets for a charged-particle beam fusion driver

A class of high-gain ICF targets driven by electrons or light ions is discussed. The targets are characterized by a low-beam-intensity requirement and large size. A magnetic field provides thermal insulation of pre-heated, low-density fuel. The addition of a cryogenic fuel layer increases the gain without requiring significantly increased beam power and intensity. The higher fuel adiabat and reduced fuel losses produce ignition and burn for lower implosion velocities and at lower power and intensity than conventional ablative designs. Gains of 20 to 40 are expected for intensities of ⪅ 80 TW·cm−2, initial magnetic fields of ⪆ 30–60 kG, an initial fuel radius of 0.2–0.4 cm, and irradiation uniformities of 6–7%. Driver requirements are ⪅ 45 TW·cm−2 if the initial magnetic field is ⪆ 300–600 kG, sufficient for alpha trapping in the compressed low-density fuel. Voltage shaping increases fuel burn-up and target ρr and lowers power and intensity levels by an additional factor of about 0.6.