Utilization of high energy, small emittance accelerators for ICF target experiments

Phase control of a z-current-driven plasma column

A dynamic mitigation is presented for sausage and kink instability growths of a z-current-driven magnetized plasma column. In this Rapid Communication we found that a wobbling motion of the z-current electron axis induces a phase-controlled perturbation, so that the growths of the sausage and kink instabilities are successfully and remarkably mitigated. In general, plasma instabilities emerge from perturbations, and the perturbation phase is normally unknown. However, if the perturbation phase is known or actively imposed by, for example, a designed driver wobbling behavior, the instability growth would be controlled and mitigated by a superimposition of the perturbations imposed. The results in this Rapid Communication demonstrate that the wobbling z-current electron beam would provide an improvement in the plasma column stability and uniformity.

Non-uniformity smoothing of direct-driven fuel target implosion by phase control in heavy ion inertial fusion

We have proposed a dynamic smoothing method based on a phase control to smooth plasma non-uniformities in perturbed plasma systems. In this paper, the dynamic smoothing method is applied to a spherical direct-driven fuel target implosion in heavy ion inertial confinement fusion. We found that the wobbling motion of each heavy ion beam (HIB) axis induces a phase-controlled HIBs energy deposition, and consequently the phase-controlled implosion acceleration is realized, so that the HIBs irradiation non-uniformity is successfully smoothed. HIB accelerators provide a well-established performance to oscillate a HIB axis at a high frequency. In inertial confinement fusion, a fuel implosion uniformity is essentially significant for achieving the DT fuel compression and for releasing the fusion energy, and the non-uniformity of the implosion acceleration should be less than a few %. The results in this paper demonstrate that the wobbling HIBs would provide an improvement in the fuel target implosion uniformity.

Rayleigh-Taylor instability in elastic solids

We present an analytical model for the Rayleigh-Taylor instability that allows for an approximate but still very accurate and appealing description of the instability physics in the linear regime. The model is based on the second law of Newton and it has been developed with the aim of dealing with the instability of accelerated elastic solids. It yields the asymptotic instability growth rate but also describes the initial transient phase determined by the initial conditions. We have applied the model to solid/solid and solid/fluid interfaces with arbitrary Atwood numbers. The results are in excellent agreement with previous models that yield exact solutions but which are of more limited validity. Our model allows for including more complex physics. In particular, the present approach is expected to lead to a more general theory of the instability that would allow for describing the transition to the plastic regime.

Statistical approach to beam shaping

A method for beam shaping based on fitting the power moments of the final beam intensity distribution and independent of the optical system particularities is suggested. It is shown how one can analytically calculate any moment of the final phase space distribution using the moments of the initial distribution and the optical system transfer map. Numerical tests carried out for a final focus system have demonstrated the usefulness of the approach developed here.