Abstract The neutral beam injection (NBI) system at Wendelstein 7-X (W7-X) was operated for the first time in 2018. Detailed calorimetric measurements were carried out to accurately determine the energy flow within the NBI system and the injected power into the plasma. Of the electric energy put into the system (89± 6) % can be accounted for. The time-averaged injected NBI power is assessed to be Pinj ≈ (3.1 ± 0.8) MW for hydrogen injection with two positive ion sources at the maximum acceleration voltage of 54 kV. This corresponds to a conversion efficiency of the initially generated ion beam power to the injected neutral beam power of about 33%. The ionization in a plasma with an ion and electron temperature of Ti ≈ Te ≈ 1.3 keV and an electron density of ne ≈ 4 ·1019 m−3 is calorimetrically determined to be about 90%. The injected power is validated against beam emission spectroscopy applying Fast-Ion Dα analysis (FIDASIM). The inferred injected power leads to an energy confinement time of around τE ≈ 150 ms for pure NBI heating plasma experiments at W7-X with these heating and plasma parameters.

中文翻译：

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Wendelstein 7-X仿星器上第一个中性射束注入器的性能

摘要 Wendelstein 7-X (W7-X) 的中性束注入 (NBI) 系统于 2018 年首次运行。进行了详细的量热测量，以准确确定 NBI 系统内的能量流和注入到等离子体。可占投入系统电能的（89±6）%。对于在 54 kV 的最大加速电压下使用两个正离子源注入氢，时间平均注入的 NBI 功率被评估为 Pinj ≈ (3.1 ± 0.8) MW。这对应于初始生成的离子束功率到注入的中性束功率的大约 33% 的转换效率。在离子和电子温度为 Ti ≈ Te ≈ 1.3 keV 和电子密度为 ne ≈ 4 ·1019 m-3 的等离子体中的电离被量热法确定为大约 90%。注入的功率通过应用快速离子 Dα 分析 (FIDASIM) 的束发射光谱进行验证。对于具有这些加热和等离子体参数的 W7-X 纯 NBI 加热等离子体实验，推断的注入功率导致大约 τE ≈ 150 ms 的能量限制时间。