Experiments comparing an internal and an external antenna H- source at the Spallation Neutron Source with and without cesium revealed key performance differences which provide insight to the source physics and will guide the development of an RF H- source at the ISIS Neutron Source. RF power sweeps were taken for each of these cases, for which the total charge, electron to H- ratio, and H- extracted per kW are all studied and plotted. At around 40 kW and typical hydrogen flow and cooling parameters, cesiated sources output 35 mA square beam pulses where uncesiated sources output 15 mA. At these settings, the beam pulse for the internal source initially overshoots, while it is flat for the external source. This observation is discussed with the difference in coupling between the antenna, the plasma, and the outlet. Sweeps of pulsed RF repetition rate and the collar temperature only affected cesiated sources, which is attributed to surface processes affecting the H- production only in the presence of cesium. Possible future experiments using a fast optical measurement and modifications to the gas flow into the external source's plasma gun and by removal of the collar assembly in uncesiated operation are discussed.

中文翻译：

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使用和不使用铯的 SNS 内部和外部天线源性能比较

比较散裂中子源的内部和外部天线 H 源的实验揭示了关键的性能差异，这些差异提供了对源物理的洞察，并将指导 ISIS 中子源的射频 H 源的开发。对这些情况中的每一种都进行了 RF 功率扫描，对这些情况下的总电荷、电子与 H- 比和每 kW 提取的 H- 都进行了研究和绘制。在大约 40 kW 和典型的氢气流量和冷却参数下，铯源输出 35 mA 方波束脉冲，而非铯源输出 15 mA。在这些设置下，内部源的光束脉冲最初会过冲，而外部源的光束脉冲则是平坦的。该观察结果与天线、等离子体和出口之间的耦合差异进行了讨论。脉冲射频重复率和轴环温度的扫描仅影响铯源，这归因于表面过程仅在铯存在时影响 H-产生。讨论了使用快速光学测量和修改进入外部源等离子枪的气流以及在未停止的操作中移除轴环组件的可能的未来实验。