| A precise knowledge of the temperature and number of hot electrons generated in the interaction of short-pulse high-intensity lasers with solids is crucial for harnessing the energy of a laser pulse in applications such as laser-driven ion acceleration or fast ignition. Nevertheless present scaling models fail to satisfactory describe for example the electron average energy for high laser intensities. We present a novel approach that is based on a weighted average of the kinetic energy of an ensemble of electrons. The scaling of electron energy with laser intensity can be derived from a general Lorentz invariant electron distribution ansatz, that does not rely on a specific model of energy absorption. We apply this ansatz on the two important cases of laser-solid interaction with and without preplasma and compare the result to former models, numerical results and experiments. The resulting scaling is in perfect agreement with simulation results and clearly follows the trend seen in recent experiments, especially at high laser intensities where other scalings fail to describe the simulations accurately. Our findings therefore give a physical interpretation of previous experimental results and assist the prediction of expected ion maximum energies for future laser systems. |
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