Sarmento Tiago, Stockli Martin, Welton Rob, Han Baoxi, Murray Syd, Pennisi Terry, Stinson Chris, Tarvainen Olli, Lawrie Scott, Faircloth Dan
ISIS Neutron and Muon Facility, STFC Rutherford Appleton Laboratory, Harwell, Oxford OX11 0QX, United Kingdom.
Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Rev Sci Instrum. 2020 Feb 1;91(2):023319. doi: 10.1063/1.5129340.
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.
在散裂中子源对带有和不带有铯的内部天线和外部天线H源进行的实验揭示了关键性能差异，这些差异有助于深入了解源物理，并将指导ISIS中子源射频H源的开发。对每种情况都进行了射频功率扫描，研究并绘制了总电荷、电子与H比以及每千瓦提取的H。在约40千瓦以及典型的氢气流量和冷却参数下，加铯源输出35毫安的方波束脉冲，而未加铯源输出15毫安。在这些设置下，内部源的束脉冲最初会超调，而外部源的束脉冲则是平坦的。结合天线、等离子体和出口之间耦合的差异对这一观察结果进行了讨论。脉冲射频重复率和套环温度扫描仅影响加铯源，这归因于表面过程仅在有铯的情况下影响H的产生。讨论了未来可能使用快速光学测量以及对流入外部源等离子体枪的气流进行修改，并在未加铯运行时移除套环组件的实验。
