Comments on the comments by Lackner et al. on the series of papers about "A novel direct drive ultra-fast heating concept for ICF"

In this paper, we provide a response to the comments made by Lackner et al. regarding our series of recent papers on "A novel direct drive ultra-fast heating concept for ICF". Specifically, we comment on the necessity of fuel pre-compression in the ICF context

Numerical validation of a volume heated mixed fuel reactor concept

In earlier papers \cite{ruhlkornarXiv,ruhlkornarXiv1,ruhlkornarXiv2} the core elements of a novel direct drive $\text{pBDT}$ mixed fuel reactor without fuel pre-compression have been discussed. The predominant purpose of the mixed fuel is to chemically bind $\text{DT}$. It has been found that the proposed mixed fuel design can reach $Q_T > 1$ with $\text{MJ}$ level external isochoric heating and without fuel pre-compression due to a novel direct drive ultra-fast heating concept. In order to further validate the concept we make use of MULTI, an ICF community code, and show with the help of MULTI simulations that the semi-analytical scaling model presented in a previous paper is capable of making accurate predictions. The MULTI simulations yield $Q_T > 1$ for a $\text{pBDT}$ fuel mix at $\text{MJ}$ level isochoric preheating, which validates our theoretical model involving in-situ compression for $Q_T \gg 1$ at reduced overall heating requirements.Comment: 5 pages, 5 figure

Uniform volume heating of mixed fuels within the ICF paradigm

The paper investigates the feasibility of achieving uniform high-power volume heating for a fusion reactor concept employing a mixed fuel composition involving $\text{pBDT}$. The realm of mixed fuel fusion concepts remains relatively unexplored. The pursuit of uniform high-power volume heating presents a technological challenge, yet it bears ramifications for fusion reactor designs. In this study, we introduce the proposition of employing embedded nano-structures that represent structured foams. These structured foams interact with short-pulse lasers, thereby achieving ultra-high power volume heating both within the fuel and the adjacent hohlraums. Notably, structured foams exhibit superior efficiency compared to unstructured foams, plasma or surfaces when it comes to absorbing high-power, short-pulse lasers. The suggested incorporation of these embedded structured foams interacting with an array of ultra-short laser pulses offers a high laser absorption power density, along with meticulous control over energy and power distribution within the fuel, both in spatial and temporal dimensions. This holds the potential for the realization of fusion reactors characterized by straight-forward designs and low complexity, where $Q_F \approx Q_T > 1$ is expected for the fuel and target gains. Depending on the fuel composition they can be strong neutron sources.Comment: 8 pages, 10 figure

High current ionic flows via ultra-fast lasers for fusion applications

In the present paper we introduce a new accelerator concept for ions. The accelerator is nano-structured and can consist of a range of materials. It is capable of generating large ionic currents at moderate ion energies. The nano-structures can be tailored towards the accelerator thus being capable of driving ion beams with very high efficiency. The accelerator is powered by laser arrays consisting of many repetitive and efficient lasers in the $100 \, \text{J}$ range with ultra-short intense laser pulses. Combining nano-structures and the proposed ultra-short pulse lasers can lead to new levels of spatio-temporal control and energy efficiency for fusion applications.Comment: 5 pages, 5 figure

High Power Gamma-Ray Flash Generation in Ultra Intense Laser-Plasma Interaction

When high-intensity laser interaction with matter enters the regime of dominated radiation reaction, the radiation losses open the way for producing short pulse high power gamma ray flashes. The gamma-ray pulse duration and divergence are determined by the laser pulse amplitude and by the plasma target density scale length. On the basis of theoretical analysis and particle-in-cell simulations with the radiation friction force incorporated, optimal conditions for generating a gamma-ray flash with a tailored overcritical density target are found.Comment: 12 pages, 5 figures Accepted for publication in Physical Review Letters (this http://prl.aps.org/