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

Abstract

A problem of accelerating pellets of significant mass with a C02-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 longwave 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 oflaboratory C02-lasers available pellet velocities up to 10-100 kmls can be obtained.

Optimum physical conditions of accelerating solid state bodies in the regime of laser ablation

“…The corresponding power density of the C02-laser which can give a temperature of 1 eV is W 2 MW/cm2. A similar power density can be achieved, for instance, in pulseperiodic rate lasers [19]. The most acceptable materials for ablator can be substances with a low specific weight (plastics, lithium, lithium deuterid, boron and etc.…”

“…At a given ablator substance a maximum effective energy conversion of laser radiation to the energy of mechanical motion of the working mass is attained when the exhaust velocity of the evaporated ablator products VE V and its expendable mass Lim' m [19].…”

“…In railguns, in spite of numerous contrivancces, the maximum attainable velocities have gained their saturation' (i.e. they are at the same level in past [15][16][17][18][19][20] years).Apparently there exist basic limitations which have not been found up yet.…”

Laser Application in the Control of Satellite Orbit

“…In this case the exhaust velocity of ionized hydrogen plasma is V E « 3 S cr (7) Where S cr is the ion sound velocity on the surface with an electron density equal to a critical one (for CCVlaser n cr = 10 19 cm" 3 ). In this case the exhaust velocity of ionized hydrogen plasma is V E « 3 S cr (7) Where S cr is the ion sound velocity on the surface with an electron density equal to a critical one (for CCVlaser n cr = 10 19 cm" 3 ).…”

“…In a number of countries (the USA, Japan, France, Germany, etc) [1][2][3][4][5][6][7] the experimental investigations are under way aimed at finding optimal variants of using powerful lasers for satellite launch including the choice of laser parameters and ablation substances, search for effective modes of conversion of laser energy to that of satellite motion.…”