帖子
勋章
关注
任务
X射线自由电子激光器可引发核聚变 多年来，科学家一直在研究通过核聚变来发电，一方面这是一种几乎取之不尽的能源，另一方面要想掌握核聚变，还有许多技术障碍。其中之一是为了引发核聚变，必须要克服聚变在一起的带相似电荷的原子核的强电排斥力，这通常需要很高能量。 但是，还有另一种方法，该项研究的合著者弗里德曼·奎塞尔说：“如果可用较低能量，通过量子力学隧道效应也可以实现聚变。这样一来，由核心排斥力引起的能垒便以较低的能量穿过隧道。”这个过程不是理论上的构建，而是一个现实，在太阳芯中发现温度和压力条件不足以克服氢核聚变的能垒，然而，通过足够数量的隧穿过程可以维持聚变反应。 HZDR科学家在他们目前的工作中研究了通过辐射对隧穿过程的支持是否可以促进受控的融合。迄今为止，用于触发此类过程的常规激光辐射的性能太低，但这状况很快就会改变。现在使用X射线自由电子激光器（XFEL），已经可以实现每平方厘米10—20瓦的功率密度。这大约相当于太阳辐射功率的1000倍，集中在1枚硬币的表面。HZDR理论物理系主任拉尔夫·许尔策豪德教授说：“这使我们进入了可以用强力X射线激光器支持这种隧穿过程的领域。” 这个想法是，导致铁心排斥的强电场，与较弱但变化迅速的电磁场叠加在一起，这可以借助XFEL产生。HZDR科学家通过氢同位素氘和氚的融合进行了理论研究。结果表明，可以通过这种方式提高隧道速率，足够数量的引发隧穿过程最终可以实现成功且受控的聚变反应。现在，当谈到未来的聚变电站概念时，该反应被认为是最有希望的反应之一。 分享到：
|
最新评论
-
likaihit 2019-12-15 00:05真的很厉害
-
redplum 2019-12-15 00:06不太可能吧
-
mang2004 2019-12-15 00:22Fusion by strong lasers
HZDR scientists want to use quantum mechanics to trigger the fusion of atomic nuclei
Nuclear physics usually involves high energies, as illustrated by experiments to master controlled nuclear fusion. One of the problems is how to overcome the strong electrical repulsion between atomic nuclei which requires high energies to make them fuse. But fusion could be initiated at lower energies with electromagnetic fields that are generated, for example, by state-of-the-art free electron lasers emitting X-ray light. Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) describe how this could be done in the journal Physical Review C.
During nuclear fusion two atomic nuclei fuse into one new nucleus. In the lab this can be done by particle accelerators, when researchers use fusion reactions to create fast free neutrons for other experiments. On a much larger scale, the idea is to implement controlled fusion of light nuclei to generate power - with the sun acting as the model: its energy is the product of a series of fusion reactions that take place in its interior.
For many years, scientists have been working on strategies for generating power from fusion energy. "On the one hand we are looking at a practically limitless source of power. On the other hand, there are all the many technological hurdles that we want to help surmount through our work," says Professor Ralf Schützhold, Director of the Department of Theoretical Physics at HZDR, describing the motivation for his research.
Tunneling at a high level, to be accessible soon
In order to trigger nuclear fusion, you first have to overcome the strong electrical repulsion between the identically charged atomic nuclei. This usually requires high energies. But there is a different way, explains the co-author of the study, Dr. Friedemann Queißer: "If there isn't enough energy available, fusion can be achieved by tunneling. That's a quantum mechanical process. It means that you can pass (i.e., tunnel) through the energy barrier caused by nuclear repulsion at lower energies."
This is not some theoretical construct; it really happens: The temperature and pressure conditions in the sun's core do not suffice to overcome the energy barrier directly and enable hydrogen nuclei to fuse. But fusion happens nonetheless because the prevailing conditions allow the fusion reaction to be sustained thanks to a sufficiently high number of tunneling processes.
In their current work, the HZDR scientists are investigating whether controlled fusion could be facilitated with the assistance of tunneling processes using radiation. But that is also a question of energy: the lower it is, the lesser the likelihood of tunneling. Up to now, conventional laser radiation intensity was too low to trigger the processes.
XFEL and electron beams to assist fusion reactions
This could all change in the near future: With X-ray free electron lasers (XFEL) it is already possible to achieve power densities of 10^20 watts per square centimeter. This is the equivalent of approximately a thousand times the energy of the sun hitting the earth, concentrated on the surface of a one-cent coin. "We are now advancing into areas that suggest the possibility of assisting these tunneling processes with strong X-ray lasers," says Schützhold.
The idea is that the strong electric field causing the nuclei repulsion is superimposed with a weaker, but rapidly changing, electromagnetic field that can be produced with the aid of an XFEL. The Dresden researchers investigated the process theoretically for the fusion of the hydrogen isotopes deuterium and tritium. This reaction is currently considered to be one of the most promising candidates for future fusion power plants. The results show that it should be possible to increase the tunneling rate in this way; a sufficiently high number of tunneling processes could eventually facilitate a successful, controlled fusion reaction.
Today, just a handful of laser systems around the world with the requisite potential are the flagships of large-scale research facilities, like those in Japan and the United States - and in Germany where the world's strongest laser of its type, the European XFEL, is to be found in the Hamburg area. At the Helmholtz International Beamline for Extreme Fields (HIBEF) located there, experiments with unique ultra-short and extremely bright X-ray flashes are planned. HZDR is currently in the process of constructing HIBEF.
The Dresden strong field physicists' next step is to dive even deeper into the theory in order to understand other fusion reactions better and be able to assess their potential for assisting tunneling processes with radiation. Analogous processes have already been observed in laboratory systems, such as quantum dots in solid-state physics or Bose-Einstein condensates, but in nuclear fusion experimental proof is still pending. Thinking yet further ahead, the authors of the study believe other radiation sources could possibly assist tunneling processes. The first theoretical results on electron beams have already been obtained.
-
dushunli 2019-12-15 00:42自由电子激光器可引发核聚变！
-
bairuizheng 2019-12-15 01:01核聚变电站总觉得很危险
-
tassy 2019-12-15 01:36不太可能吧
-
daite1978 2019-12-15 08:59核聚变电站总觉得很危险
-
谭健 2019-12-15 09:32真的很厉害
-
mmttxiaoxiao 2019-12-15 10:41攻克技术难点
-
tomryo 2019-12-15 11:10X射线自由电子激光器可引发核聚变
12