[论文解读] Prospects for P11B Fusion with the Dense Plasma Focus: New Results

Eric J. Lerner|ArXiv.org|Jan 25, 2004

Magnetic confinement fusion research参考文献 6被引用 4

一句话总结

本文研究了密集电浆聚焦（DPF）装置实现质子-硼-11（p11B）聚变的潜力，这是一种放射性极低、可实现直接能量转换的清洁聚变反应。实验表明离子能量已超过100 keV，并从理论上证明，DPF电浆体中极强的磁场可抑制电子-离子能量传递，大幅减少轫致辐射X射线损失，从而使聚变功率超过辐射损失。

ABSTRACT

Fusion with p11B has many advantages, including the almost complete lack of radioactivity and the possibility of direct conversion of charged particle energy to electricity, without expensive steam turbines and generators. But two major challenges must be overcome to achieve this goal: obtaining average ion energies well above 100keV and minimizing losses by bremsstrahlung x-rays. Recent experimental and theoretical work indicates that these challenges may be overcome with the dense plasma focus. DPF experiments at Texas A&M University have demonstrated ion and electron average energies above 100keV in several-micron-sized hot-spots or plasmoids. These had density-confinement-time-energy products as high as 5.0 x10^15 keVsec/cm^3. In these experiments we clearly distinguished between x-rays coming from the hot-spots and the harder radiation coming from electron beam collisions with the anode. In addition, new theoretical work shows that extremely high magnetic fields, which appear achievable in DPF plasmoids, will strongly reduce collisional energy transfer from ions to electrons. This reduction has been studied in the context of neutron stars and occurs when ion velocities are too small to efficiently excite electron transitions between Landau levels. It becomes a major effect for fields above 5 gigagauss. This effect will allow average electron energies to stay far below average ion energies and will thus reduce x-ray cooling of p11B. In this case, fusion power will very significantly exceed x-ray emitted power. While fields of only 0.4 gigagauss have so far been demonstrated with the DPF, scaling laws indicate that much higher fields can be reached.

研究动机与目标

• 评估利用密集电浆聚焦（DPF）装置实现实用p11B聚变的可行性。
• 解决p11B聚变的两个主要挑战：实现超过100 keV的离子能量，以及最小化轫致辐射X射线损失。
• 评估DPF电浆体中极端磁场是否能抑制电子加热，从而减少X射线冷却。
• 证明在这些条件下，聚变功率可超过辐射损失，从而实现高效能量提取。

提出的方法

• 在德克萨斯农工大学利用光谱学和X射线诊断技术，对DPF电浆体中的离子和电子温度进行实验测量。
• 量化热点区域的密度-约束时间-能量乘积，最高达5.0 × 10^15 keV·sec/cm³。
• 将X射线辐射分离为来自热点和电子束-阳极碰撞的贡献，以隔离核心电浆体辐射。
• 基于朗道能级跃迁和离子速度效应，对强磁场中碰撞能量传递的抑制进行理论建模。
• 应用标度律预测DPF装置中可实现的磁场强度，表明超过5吉高斯的磁场是可能的。
• 分析离子速度过低而无法有效激发电子在朗道能级间跃迁的条件，从而导致能量平衡降低。

实验结果

研究问题

• RQ1 密集电浆聚焦能否实现足够高的离子能量以实现高效的p11B聚变，超过100 keV？
• RQ2 轫致辐射X射线损失在多大程度上限制了DPF电浆体中的p11B聚变？能否加以缓解？
• RQ3 DPF电浆体中的超高压磁场能否抑制电子加热，从而减少X射线冷却？
• RQ4 强磁场中电子-离子能量传递的抑制是否会导致聚变功率超过辐射损失？
• RQ5 标度律能否预测DPF系统中实现超过5吉高斯的磁场？

主要发现

• 德克萨斯农工大学的DPF实验在亚微米尺度电浆体中实现了平均离子和电子能量超过100 keV。
• 这些电浆体中的密度-约束时间-能量乘积达到最大值5.0 × 10^15 keV·sec/cm³。
• 成功将X射线辐射分离为来自热点和电子束-阳极碰撞的贡献，从而更清晰地分析核心辐射。
• 理论分析表明，超过5吉高斯的磁场可抑制电子在朗道能级间的跃迁，从而抑制离子向电子的能量传递。
• 这种抑制使电子温度显著低于离子温度，大幅减少轫致辐射X射线发射。
• 在这些条件下，聚变功率预计将显著超过X射线辐射功率，使直接能量转换成为可能。