The influence of semi-spherical cavities of different sizes was investigated for the enhancement of propulsion parameters in conjunction with pulsed Nd:YAG laser operating at 1064 nm. The 10 mm, 11.5 mm, 15 mm, 18.5 mm and 20 mm cavities of iron were used to confine the laser-induced plasma. Aluminum (Al), Silver (Ag), and Gold (Au) samples in form of foils were used as propellants. A significant enhancement in momentum coupling coefficient (C_m) and specific impulse (I_sp) was observed when cavities were used to confine the laser-induced plasma. From the measurements obtained for various sizes of cavities, it was observed that C_m and I_sp recorded the highest values for the 10 mm cavity. Therefore, the confinement effect was most significant for the smallest cavity. In confinement geometry the value of C_m increased from 16.9 to 39.6 (dyne/W) for Al, from 13.1 to 30.6 (dyne/W) for Ag and from 12.9 to 34.5 (dyne/W) for Au target respectively, while the value of I_sp increased to nearly 40,000 s with the confined geometry, as compared with 3000 s for direct propulsion. Results demonstrated that due to uniform and balanced compression of shockwaves in all directions, semi-spherical cavities played a significant role in the enhancement of laser ablation propulsion parameters. This may introduce new avenues to tune the specific impulse and thrust in micropropulsion applications.

结合在 1064 nm 工作的脉冲 Nd:YAG 激光器，研究了不同尺寸的半球形腔对推进参数的影响。10 mm、11.5 mm、15 mm、18.5 mm 和 20 mm 的铁腔用于限制激光诱导的等离子体。箔形式的铝 (Al)、银 (Ag) 和金 (Au) 样品用作推进剂。当腔体用于限制激光诱导等离子体时，观察到动量耦合系数 ( C _m ) 和比冲 ( I _{sp ) 显着增强。}根据对各种尺寸的空腔获得的测量结果，观察到C _m和I _sp记录了 10 mm 腔的最高值。因此，对于最小的空腔，约束效果最为显着。在限制几何中，Al 的C _m值从 16.9 增加到 39.6 (dyne/W)，Ag 从 13.1 增加到 30.6 (dyne/W)，Au 目标从 12.9 增加到 34.5 (dyne/W)。I _sp在受限几何形状下增加到近 40,000 秒，而直接推进则为 3000 秒。结果表明，由于冲击波在各个方向上的均匀和平衡压缩，半球形腔在提高激光烧蚀推进参数方面发挥了重要作用。这可能会引入新的途径来调整微推进应用中的比冲和推力。