观测热核聚变反应中的氘-氘融合
Observation of Thermal Deuteron-Deuteron Fusion in Ion Tracks
AI总结：
本研究通过实验观测到热核聚变反应中的氘-氘融合现象，并通过理论模型解释了电子屏蔽效应和离子轨迹形成对反应率的影响。
摘要：
直接观测氘-氘（DD）融合反应在热meV能量下的现象，尽管在理论上是可能的，但直到现在尚未成功。电子屏蔽效应通过在金属环境中减少反应核之间的排斥库仑势垒几百电子伏特，并且在宿主材料中的晶体晶格缺陷进一步增加，导致了显著增强的截面，这意味着这种效应可能在实验室中研究。我们在此报告了在ZrD2靶上进行的2H（d，p）3H反应测量结果，使用超高压真空加速器系统，最近升级以实现非常低能量下的高束流。实验厚靶产量在降低束能时下降了七个数量级，可以很好地用340 eV的电子屏蔽能来描述，这比无缺陷材料的约100 eV的值要高得多。在低于2.5 keV的能量下，可以观察到恒定的平台产量值。正如发射质子的显著增加能量所指示的，这种效应可以与热DD融合相关联。一个理论模型通过由弹丸诱导在靶中产生的离子轨迹以及局部提高温度超过熔点的高声子密度来解释实验观测。考虑到最近观察到的DD阈值共振的核反应率与实验数据非常吻合。
英文摘要：
A direct observation of the deuteron-deuteron (DD) fusion reaction at thermal meV energies, although theoretically possible, is not succeeded up to now. The electron screening effect that reduces the repulsive Coulomb barrier between reacting nuclei in metallic environments by several hundreds of eV and is additionally increased by crystal lattice defects in the hosting material, leads to strongly enhanced cross sections which means that this effect might be studied in laboratories. Here we present results of the 2H(d,p)3H reaction measurements performed on a ZrD2 target down to the lowest deuteron energy in the center mass system of 675 eV, using an ultra-high vacuum accelerator system, recently upgraded to achieve high beam currents at very low energies. The experimental thick target yield, decreasing over seven orders of magnitude for lowering beam energies, could be well described by the electron screening energy of 340 eV, which is much higher than the value of about 100 eV for a defect free material. At the energies below 2.5 keV, a constant plateau yield value could be observed. As indicated by significantly increased energies of emitted protons, this effect can be associated with the thermal DD fusion. A theoretical model explains the experimental observations by creation of ion tracks induced in the target by projectiles, and a high phonon density which locally increases temperature above the melting point. The nuclear reaction rate taking into account recently observed DD threshold resonance agrees very well with the experimental data.
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