Thrust Measurement for Laser-Detonation Propulsion with a Solid-State Laser
Thrust Measurement for Laser-Detonation Propulsion with a Solid-State Laser
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DOI：
10.2514/1.b34585
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发表时间：
2013-01
影响因子：
1.9
通讯作者：
Bin Wang;K. Michigami;K. Komurasaki;Y. Arakawa
中科院分区：
文献类型：
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作者：
Bin Wang;K. Michigami;K. Komurasaki;Y. Arakawa
在激光爆轰推进[1]中，推进器被设计为在大气层飞行期间使用大气作为推进剂，这使得有效载荷分数显着增加。从地面激光设施发射的高功率激光脉冲集中在推进器底部引起爆炸，从而产生推进脉冲。激光器的选择是激光爆轰推进中的一个重要问题。据估计，要将质量达数公斤的纳米卫星发射到低地球轨道（LEO），必须使用平均输出为1 MW的高功率激光器。早期的研究专门研究了使用横向激发大气压 (TEA) CO2 激光器作为电源 [2,3]。测得的动量耦合系数 Cm（定义为获得的推进脉冲 I 与输入激光能量 Ei 之比）在各种推进器喷嘴下约为 0.3–0.4 mN·s∕J [2,4,5]。然而，高功率固态激光技术的最新进展使其成为实现任务要求的可能替代方案。正如国家点火装置所证明的那样，已经实现了兆焦耳级脉冲能量[6]。此外，固态激光器的工作机制使得在重复性脉冲激光推进发射任务中使用一组具有良好同步性的激光器组合使用比使用TEA-CO2激光器更可行。这两种激光器的主要区别在于激光能量吸收系数，它与激光波长λ的立方成正比； TEA-CO2 激光器的 λ 为 10.6 μm，钕玻璃（Nd:glass）激光器的 λ 为 1.053 μm。作者的早期工作[7]表明，无论波长差异如何，固态激光器从照射激光能量Ei到诱导冲击波能量Ebw的能量转换效率ηbw（等于Ebw∕Ei）与CO2激光实验中测得的能量转换效率[8]近似，如表1所示。这里，冲击波能量定义为在热量完美条件下驱动等效冲击波所需的源能量。气体。这一成果为固体激光器未来发射激光爆轰推进器奠定了基础。本注释描述了使用固态激光器进行的激光推进脉冲测量。通过与 CO2 激光实验中的比较，讨论了推力性能及其对喷嘴尺寸的依赖性。还研究了焦点位置的影响。
I N LASER-detonation propulsion [1], a thruster is designed to use the atmosphere as propellant during its atmospheric flight, which enables a considerable increase in the payload fraction. High-power laser pulses irradiated from a ground-based laser facility are concentrated to induce explosions at the thruster bottom, thereby producing a propulsive impulse. Selection of the laser is an important issue in laser-detonation propulsion. As estimated, for launching a nanosatellitewith amass of several kilograms into low earth orbit (LEO), a high-powered laser with 1 MW average output must be used. Earlier studies have specifically examined using a transversely excited atmosphericpressure (TEA) CO2 laser as a power source [2,3]. The measured momentum-coupling coefficient Cm, defined as the ratio of the obtained propulsive impulses I to the input laser energy Ei, was around 0.3–0.4 mN · s∕J with various thruster nozzles [2,4,5]. However, recent progress made in high-power solid-state laser technology makes it a possible alternative to achieve mission requirements. As demonstrated at the National Ignition Facility, megajoule-level pulse energy has been achieved [6]. In addition, the working mechanism of solid-state laser makes it more feasible to use a group of lasers for use in combination with good synchronicity in a repetitive pulsed laser-propulsion launch mission than using a TEA-CO2 laser. The major difference between these two lasers is the laser energyabsorption coefficient, which is proportional to the cube of the laser wavelength λ; λ 10.6 μm for TEA-CO2 laser and 1.053 μm for a neodymium glass (Nd:glass) laser. The author’s earlier work [7] demonstrated that, irrespective of the wavelength difference, the energy-conversion efficiency ηbw (equal to Ebw∕Ei) from the irradiated laser energyEi to the induced blast-wave energyEbwwith a solid-state laser approximates that measured in the CO2 laser experiments [8], as shown in Table 1. Here, the blast wave energy is defined as the source energy that is necessary to drive an equivalent blast wave in a calorically perfect gas. This result has laid the foundation for the application of a solid-state laser to the future launch of laser-detonation thrusters. This Note describes laser-propulsion impulse measurements conducted using a solid-state laser. The thrust performance and its dependence on the nozzle scale are discussed in comparison with those in the CO2 laser experiments. The influence of the focus position was also investigated.