Garbuny M, Pechersky M J
Appl Opt. 1976 May 1;15(5):1141-57. doi: 10.1364/AO.15.001141.
The coherence properties and power levels of lasers available at present lend themselves to the remote operation of mechanical engines by resonance absorption in a working gas. Laser radiation is capable of producing extremely high temperatures in a gas. Limits to the achievable temperatures in the working gas of an engine are imposed by the solid walls and by loss of resonance absorption due to thermal saturation, bleaching, and dissociation. However, it is shown that by proper control of the laser beam in space, time, and frequency, as well as by choice of the absorbing gas, these limits are to a great extent removed so that very high temperatures are indeed attainable. The working gas is largely monatomic, preferably helium with the addition of a few volume percent of an absorber. Such a gas mixture, internally heated, permits an optimization of the expansion ratio, with resulting thermal efficiencies and work ratios, not achievable in conventional engines. A relationship between thermal efficiency and work ratio is derived that is quite general for the optimization condition. The performance of laser piston engines, turbines, and the Stirling cycle based on these principles is discussed and compared with conventional engine operation. Finally, a brief discussion is devoted to the possibility and concepts for the direct conversion of selective vibrational or electronic excitation into mechanical work, bypassing the translational degrees of freedom.
目前可用激光器的相干特性和功率水平使其能够通过工作气体中的共振吸收来远程操作机械发动机。激光辐射能够在气体中产生极高的温度。发动机工作气体中可达到的温度极限受到固体壁以及由于热饱和、漂白和解离导致的共振吸收损失的限制。然而，研究表明，通过在空间、时间和频率上对激光束进行适当控制，以及选择吸收气体，这些限制在很大程度上得以消除，从而确实能够达到非常高的温度。工作气体主要是单原子的，最好是氦气，并添加体积百分比为百分之几的吸收剂。这种内部加热的气体混合物能够优化膨胀比，从而获得传统发动机无法实现的热效率和功比。推导了在优化条件下热效率和功比之间相当通用的关系。讨论了基于这些原理的激光活塞发动机、涡轮机和斯特林循环的性能，并与传统发动机运行进行了比较。最后，简要讨论了绕过平动自由度将选择性振动或电子激发直接转化为机械功的可能性和概念。
