激光制导闪电——人类偿试驾驭闪电迈出了一大步|Laser lightning Rod,Laser -guided lightning

金蛇狂舞，雷动九天，雷电是天地间最超凡的自然现象，同时也极具破坏力，诸如引发森林大火和大范围停电，每年在全世界造成大量的生命和财产损失。传统的避雷针保护范围非常有限，只能保护半径仅相当其高度的区域，无法保护大范围敏感场所，如机场、火箭发射场、核电站等等。

对于这个问题，来自日内瓦大学、快通激光器公司等机构的科学家们给出了解决方案。近日，他们在瑞士桑蒂斯山顶进行的试验证明，高功率激光束可以成为导引闪电的路径，可以将传统的避雷针以虚拟的方式向空中延申，从而可以扩大避雷针的保护范围。

这个名为激光避雷针或简称LLR的研究项目将一台汽车大小的激光器放在瑞士海拔 2,502 米的桑蒂斯山顶，测试集中在山顶上高124 米的电信发射塔上。当极高功率的激光脉冲发射到大气中时，光束内部会形成非常强的光丝，这些光丝使空气电离，释放出可以自由移动的电子，这种被称为“等离子体”的电离空气就变成了导电体，从而成为引导闪电的路径。

在持续数周的夏季暴风雨中，激光形成的大气通道累计在六个小时内转移了四道闪电。高速摄像机从其中一次雷击的两个不同角度捕捉的图像清晰地显示了闪电在到达塔顶之前顺着激光通道行进了超过60米。这意味着激光束将避雷针的保护区域半径从 120 米增加到了180 米。

该技术应用了一种新的激光器，其平均功率为 1 千瓦，每个脉冲为 1 焦耳，每个脉冲持续时间为 1 皮秒，一皮秒也叫微微秒，就是万亿分之一秒。激光棒宽 1.5 米，长 8 米，重量超过 3 吨，由通快科学激光器公司设计。研究者认为，以前很多类似实验之所以没有成功，是因为极其快速的激光脉冲至关重要，这些激光脉冲的速度会在关键时刻使大气发生变化，从而产生有利于放电的热空气柱。

这项研究成果发表在2023年1月6日的自然光子学期刊上。研究者称，这是一种可用于保护超大型建筑物的技术，成本约为100万欧元。可以部署强大的激光器来帮助保护机场和发射台等敏感地点。当火箭必须从发射台撤回以降低雷击风险时，延误的代价是昂贵的。

该研究团队的下一步目标是进一步提高激光器的作用高度， 使最终效果相当于将一根10 m 高的的避雷针向天空延申500 m。
The golden snake dances wildly, and thunder strikes the nine heavens. Thunder and lightning are the most extraordinary natural phenomena in the world, but they are also extremely destructive, such as causing forest fires and large-scale power outages, causing a large number of lives and property losses around the world every year. The protection range of traditional lightning rods is very limited. It can only protect the area whose radius is only equivalent to its height, and cannot protect large-scale sensitive places, such as airports, rocket launch sites, nuclear power plants, etc. For this problem, scientists from the University of Geneva, Kuaitong Laser Company and other institutions have given a solution. Recently, they conducted experiments on the top of Santis Mountain in Switzerland to prove that high-power laser beams can be used as a path to guide lightning, and the traditional lightning rod can be extended into the air in a virtual way, thereby expanding the protection range of the lightning rod. The research project, known as the Laser Lightning Rod, or LLR for short, placed a car-sized laser on top of the 2,502-meter-high mountain in Santis, Switzerland, and the tests focused on a 124-meter-tall telecommunications tower atop the mountain. When extremely powerful laser pulses are fired into the atmosphere, very intense filaments of light form inside the beam. These filaments ionize the air, releasing electrons that can move freely. This ionized air is called a "plasma." It becomes an electrical conductor, thus becoming the path that guides the lightning.
Cumulatively, the laser-created atmospheric channel diverted four bolts of lightning over a six-hour period during the weeks-long summer storm. Images captured by a high-speed camera from two different angles of one of the strikes clearly show the lightning traveling more than 60 meters down the laser tunnel before reaching the top of the tower. This means that the laser beam increases the radius of the lightning rod's protective field from 120 meters to 180 meters. The technique uses a new laser with an average power of 1 kilowatt, each pulse is 1 joule, and each pulse lasts 1 picosecond, or a trillionth of a second. The laser bar is 1.5 meters wide, 8 meters long and weighs more than 3 tons, and was designed by TRUMPF Scientific Lasers.