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The concept of a power plant for fast-ignition heavy ion fusion is developed. It is based on repetitive detonation of a cylindrical direct-drive target, producing 750 MJ of fusion yield in each microexplosion. A heavy-ion driver system providing consequent compression and ignition of the cylindrical DT target is described. Data on energy fluxes generated by the microexplosion are given. The design of the thin liquid wall reactor chamber is presented. The behaviour of the liquid film at the first wall and the blanket coolant and material under a pulsed energy flux loading is analysed. The energy conversion thermal scheme and power plant output parameters are presented. The state of the art at the ITEP-TWAC experimental accelerator is described.

The concept of a power plant for a fast ignition heavy ion fusion is briefly reviewed. The reactor chamber response to x-ray irradiation, ion debris and neutron flux is considered. Ablation of a thin liquid film at the first wall is simulated by means of a one-dimensional hydrodynamic code. Ion debris reheating of the vaporized coolant is evaluated. Vaporization and subsequent condensation of the coolant is computed with the use of a kinetic model of fast condensation. Heating of the blanket due to neutron deposition and corresponding generation of pressure and stress waves are simulated by means of the Monte Carlo (MCNP) code and by the strength media mechanics code, respectively.

Ignition conditions in axially magnetized cylindrical targets are investigated by examining the thermal balance of assembled DT fuel configurations at stagnation. Special care is taken to adequately evaluate the energy fraction of 3.5 MeV alpha particles deposited in magnetized DT cylinders. A detailed analysis of the ignition boundaries in the ρR,T parametric plane is presented. It is shown that the fuel magnetization allows a significant reduction of the ρR ignition threshold only when the condition BR 6 × 105G cm is fulfilled (B is the magnetic field strength and R is the fuel radius).

Scaling of the ignition energy threshold Eig with the implosion velocity vim and isentrope parameter α of imploding spherical DT shells is investigated by performing one dimensional (1-D) hydrodynamic simulations of the implosion and hot spot formation dynamics. It is found that the a and b exponents in the power law approximation Eig ∝ αavim-b depend crucially on the subset of initial configurations chosen to establish the scaling law. When the initial states are generated in the same way as in the Livermore study (W.K. Levedahl, J.D. Lindl, Nucl. Fusion 37 (1997) 165), the same scaling, Eig ∝ α1.7 vim-5.5, is recovered. If, however, the initial states are generated by rescaling the parent configuration according to the hydrodynamic similarity laws, a different scaling is obtained, Eig ∝ α3.0 vim-9.1, which is very close to the α3vim-10 dependence predicted by the simple isobaric model for assembled fuel states. The latter is more favourable than the Livermore scaling when rescaling the fusion capsules to higher implosion velocities, but requires the peak drive pressure to be increased as P ∝ vim5.

A new gain model based on an adiabatic self-similar solution of the hydrodynamic equations is proposed for inertial confinement fusion (ICF) targets ignited by means of a thermonuclear spark at the fuel centre. The model is applied to analyse gain curves corresponding to fixed values of the implosion velocity Uim. It is shown that the adequate ignition criterion, allowing for the inertia of the cold fuel, implies ρsRsTs varies as Uim at the time of ignition, as contrasted to fixed values of the spark areal density, ρsRs, and the temperature, Ts, assumed in many of the earlier publications. The modified ignition condition leads to the scaling Emin varies as α3Uim-7 and Gf* varies as (E/α3)0.4 for the ignition energy threshold, Emin, and the limiting fuel gain, Gf*, of ICF capsules; α is the isentrope parameter of the cold fuel, E is the energy invested in the DT fuel. Stability and symmetry constraints do not affect this scaling when the initial aspect ratio of the fusion capsule A0 >> 1; in the opposite case of initially thick capsule shells, the scaling of Emin and Gf* with Um, and α becomes ill defined

Admissible values of the temperature Ts and the confinement parameter Hs = ρsRs, of a hot thermonuclear spark in DT and D2 fuels have been investigated. It is shown that it is not possible to achieve spark ignition of pure deuterium targets. Numerical simulations of precompressed DT and D2 microspheres (bare or tamped with a gold shell) have been performed and the values of the spark factor fs (ratio of thermonuclear energy gains that can be achieved in optimal core ignited and volume ignited targets) have been calculated. For a few milligrams of equimolar DT mixture the spark factor is shown to be 1.8-1.9, while for 10 mg D2 microspheres it is below 1.2.