Macroparticle acceleration in the regime of laser-driven rocket traction and the possibility to conduct experiments using CO2 laser

A problem of accelerating pellets of significant mass with a CO 2 -laser pulse (or a pulse train) is under consideration. As it is known, the highest magnitudes of the accelerated pellet velocity of about 100 km/s were observed in the experiments on accelerating flat foils with a nanosecond Nd-laser pulse. The acceleration efficiency achieved was 5 - 10%. However the accelerated target usually turned into a cloud of superdense low-temperature plasma in these experiments. To avoid pellet destruction and to achieve maximum acceleration it is necessary, depending on the task stated, to meet certain requirements to the laser wave-length, power density and pulse duration. So, for instance, to accelerate pellets of frozen hydrogen only long-wave lasers can be used. When pellets of other materials are to be accelerated the wave length range used can be broadened. However, the laser pulse duration must be large enough to avoid shock wave formation. The regime of laser-driven rocket traction seems to be the most acceptable. Difficulties in attaining this regime in the experiment mainly concern formation of a uniform and extended in the atmosphere laser beam. Acceleration of frozen hydrogen pellets for fuel injection in thermo-nuclear setups with magnetic confinement are discussed. It is shown that on the basis of laboratory CO 2 -lasers available pellet velocities up to 10 - 100 km/s can be obtained.