##### Title : Non-thermal presssures in extreme CPS laser pulses for alternative ignition of nuclear fusion

#### Abstract:

Following the recent result of a possible design may lead to electric power stations with nuclear energy from fusion of hydrogen H with the boron isotope eleven (HB-11fusion) withoutt any primary radioactive radiation emission,.This nuclear reaction energy is about ten million times higher than from burning carbon. This energy difference is the reason why the chemical reaction can be ignited thermally at pressures by a match and the nuclear reaction needs temperatures of dozens of millions 0C, aimed with ITER not before 2040. In contrast are the new results that instaed of the thermal pressures, focussed laser beams can produce alternative non-thermal pressures with laser pulses now for laser boron fusion as we know from nonlinear force driven plasma block acceleration, first calcultated in 1978 and measured in 1996 by Sauerbrey using picosecond CPA laser pulses. It took a long time until energy densities above 6 Terajoule/ccm. The modern civilization is based on the energy source of burning carbon. This leads to climate change with the problem of existential survival. One option is to use nuclear energy that produces ten million times more energy per reaction than the chemical energy from coal. One option for nuclear energy is the fission of uranium nuclei by neutrons where reactors are on the market producing now more than 10% of all electricity. The other energy source is the fusion of very light nuclei to melt them together into heavier (fusion) as this is the energy source of myriads of stars in the Universe. In view of the million times highes reaction energy, the ignition cannot be done at temperatures of several 100 oC as with burning of coal, but one needs temperatures of dozens of million oC. This has been shown during the last 60 years but each reaction with plasmas confined by magnetic fields of several tesla or by inertial compression and heatng (IEC) using lasers were far too short that a power reactor cannot be expected for very many years. A radical change of this situation is now neverless open thanks to avoiding of the high temperatures above of the million degrees Celsius by using the just reached ultra-extreme CPA (Chirped Pulse Amplification) laser pulses for LASER BORON FUSION without the problems of dangeous nuclear radiation. The equation of motion for the force density f in hightemperature plasmas is given by hydrodynamics for nuclear fusion consists of a first term with the gas dynamic pressure p given by the density and the thermal equilibrium temperature T. This is in the range below eV (electronvolt = 8560 oC) as chemical energy when burning coal, but is at about ten million times higher for thermally igniting nuclear fusion. These many dozens of million degree Celsius oC and was well reached with magnetic plasma confinement in tokamaks or stellarators or in laser driven spherical compression by nanosecond pulses, but too short for generating electricity. Apart from the first term with the thermal pressure p, the presence of electric and magnetic fields and plasma-optical responses can generate the non-thermal electromagnetic nonlinear force fNL. This could directly be seen in the experiments by Sucov at laser interaction in Figure 1 resulting first in the non-transient equation of motion with Maxwell’s plasma stress tensor needing additional nonlinear terms. Finally after clarifying six controverisl solutions the Lorentz and gauge invariant was derived. Evaluating about 500 pictures like Fig. 1 for different laser pulse energies, pulse durations and sphere diameters showed the central plasma thermally expanding with temperaures around 20 eV fully following the expected thermal plasma propeerty of the heated sphere taking the varying energy depending on the cases of the interacting 90% laser energy.The maximum energy of the ions in the half-moons were in the range up to 5 keV showing a non-thermal behaviour. This definitely could not be from bremsstrahlung in the corresponding range of 20 MeV tempeature. Very detailled hydrodynamic computation of plane geometry condition of deuterium plasma at 1017 W/cm2 laser intensity up to the critical density during 1.5 ps laser irradiation showed a plasma block acceleration of 1020 cm/s2 . This ultrahigh acceleration against the direction of the laser beam was measured from blue Doppler-shifted spectral lines by Sauerbrey using CPA laser pulses for which discovery the 2018 Physics Nobel Prize was awarded to Donna Strickland and Gerard Mourou. The nonlinear force driven acceleration was about 100,000 times higher than thermally accelerted by the NIF laser.One highlight of non-thermal energy density by nonlinear force conditions against the thermal energy density with plasma temperaures of hundred Million oC is the measururement by Sven Steinke where 18nm thin diamond films absorbed 99% energy of laser pulses and produces an energy density of 6.55x1012 J/cm3. This is much higher than the hundred million degrees of thermal equilibrium ignition especially for the very low gains of hydrogen H with the boron isotope 11 (HB11 reaction) that is primarily environmnatally clean without radioacitvity. This supports the design and is the basis for an absolutely clean, safe, low-cost and abundant electricity generator.