When the working gas of a negative ion source is changed from hydrogen to its isotope, deuterium, an 'isotope effect' is observed; namely, several plasma characteristics such as the electron energy distribution, the atomic fraction and the spectra of rovibrationally excited molecules change. The understanding of the effect becomes more important, as research and development aiming at ITER power level operation is being challenged with feeding deuterium to the ion sources. As a historical review of the effort to develop hydrogen/deuterium negative ion sources, several types of negative ion sources designed for the neutral beam plasma heating are described: double charge exchange sources, volume sources and surface-plasma sources. The early results with volume sources operated with and without cesium are introduced. The characteristics of the source charged with deuterium are compared to those of the source charged with hydrogen. The isotope effect did not appear pronounced as the negative ion density was measured in a small source but became more pronounced when the plasma source size was enlarged and the discharge power density was increased to higher values. Surface plasma sources were optimized for deuterium operation but could not achieve the same performance as a source operated with hydrogen at the same power and pressure. The lower velocity of negative deuterium ions leaving the low work function surface seemed to limit the production efficiency. Fundamental processes causing these differences in negative ion source operation are summarized. After explaining the current status of negative ion source research and development, the acquired knowledge is utilized to the development of large negative ion sources for nuclear fusion research and to the development of compact negative ion sources for neutron source applications.

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使用氘进行负离子源操作

当负离子源的工作气体由氢变为其同位素氘时，观察到“同位素效应”；即，若干等离子体特性如电子能量分布、原子分数和振动激发分子的光谱发生变化。对这种效应的理解变得更加重要，因为针对 ITER 功率级操作的研究和开发正面临着向离子源输送氘的挑战。作为对开发氢/氘负离子源的努力的历史回顾，描述了为中性束等离子体加热设计的几种类型的负离子源：双电荷交换源、体积源和表面等离子体源。介绍了使用和不使用铯操作的体积源的早期结果。将充有氘的源的特性与充有氢的源的特性进行比较。当在小源中测量负离子密度时，同位素效应并不明显，但当等离子体源尺寸增大且放电功率密度增加到更高值时，同位素效应变得更加明显。表面等离子体源针对氘操作进行了优化，但无法实现与在相同功率和压力下使用氢气操作的源相同的性能。离开低功函数表面的负氘离子的较低速度似乎限制了生产效率。总结了导致这些负离子源操作差异的基本过程。在说明了负离子源研发的现状后，