实验室电火花可产生X射线

Sparks created in a lab give off X-rays, scientists announced Monday.

X-rays are a byproduct of high-energy electron discharges in the Sun, in exploding stars, and even in lightning. Many scientists did not expect sparks alone to do the trick.

Researchers at Florida Institute of Technology brought their equipment, which had detected X-rays in lightning, into the lab. Half the team expected to see X-rays and the other half did not.

In sparks of 1.5 million to 2 million volts¹, the researchers indeed recorded X-rays that were remarkably² similar to those produced by lightning.

"This amazed us. It opens the door to answering really big questions about lightning by generating it in the lab," said team member Hamid Rassoul. "It also tells us that we have a lot to learn about how even small sparks work."

X-rays are a form of electromagnetic radiation, on a spectrum³ that runs from radio waves on the low end to gamma rays on the high end and includes visible light, too.

Scientists don't know why lightning spawns⁴ X-rays. They theorize it involves a "runaway⁵ breakdown⁶" of the air, in which electrons escape their normal bonds and gain very large energies.

"We didn't think [X-rays] could be made so easily in the air," said study leader Joseph Dwyer. "The results should allow for the detailed⁷ laboratory study of runaway breakdown, a mechanism⁸ that may play a role in thunderstorm electrification⁹, lightning initiation¹⁰ and propagation, and terrestrial gamma-ray flashes."

　　中文：

　　美国科学家日前宣布说，他们在实验室中制造出的电火花能够发射出X射线。X射线是太阳、爆炸星体甚至闪电中的高能电子放电带来的副产品，很多科学家并不认为电火花独自也能产生出这种射线。

　　据美国“生活科学网”日前报道，美国佛罗里达理工学院的研究人员将他们曾在闪电中发现X射线的试验设备带到了一个实验室中。试验进行之前，有一半的研究人员期待着实验室中产生的电火花也能发射出X射线，但是另一些人则对此不抱希望。

　　试验过程中，研究人员在150万伏特至200万伏特的电火花中确实发现了X射线，而且这种X射线和那些由闪电产生的X射线极其相似。对此，研究小组成员哈米德·拉瑟尔表示，“这让我们感到吃惊。它有助于我们回答一些关于闪电的重大问题。这也告诉我们，即使对于小小的电火花，我们仍然有很多需要了解的”。

　　报道说，X射线是电磁辐射的一种形式。而目前科学家们尚不清楚为何闪电会产生X射线。他们推测这涉及到一种空气的“逃逸崩溃”，即空气中的电子逃脱了其正常联结，同时获得了非常大的能量。此项研究的负责人约瑟夫·德怀尔说，“以前我们没想到X射线可以在空气中如此轻易地被制造出来。这些结果将使我们对‘逃逸崩溃’进行更为深入细致的实验室研究”。