For performing a study of impurity transport efficiently by using a Tracer-Encapsulated Solid Pellet (TESPEL) in Large Helical Device (LHD), a new double-barreled TESPEL injection system was recently developed and installed on the LHD. The TESPEL in each injection line can be injected with different timing and acceleration pressure which can be set individually. To prevent the high-pressured gas for the TESPEL acceleration from getting into the vacuum vessel of the LHD, a 3-stage differential pumping scheme was applied. Since the available space is very limited, the 3-stage differential pumping system is shared with each TESPEL injection line. And for the same reason, one of the guide tubes in one injection line of the new TESPEL injection system was purposely bent (bending radius of about 40 m). The guide tubes in the other injection line of the new TESPEL injection system are straight. We performed a laboratory test to check the TESPEL transferring capability with the guide tubes in the new injection system. The points of TESPEL impact on the target foil are found to be within the circles defined by a possible pellet divergence full angle, 2 degrees. Therefore, we confirmed that the TESPEL can pass through both the slightly bent and the straight injection lines of the new injection system without any problem. The blank shot test shows that the increment of the total pressure even by using both the injection lines simultaneously is much below the base pressure of the LHD vacuum vessel during the discharge. This result successfully demonstrated the capability of the applied 3-stage differential pumping scheme in the new injection system.

为了通过在大型螺旋装置 (LHD) 中使用示踪剂封装的固体颗粒 (TESPEL) 有效地进行杂质传输研究，最近开发了一种新的双管 TESPEL 注射系统并安装在 LHD 上。每条注射线中的 TESPEL 可以以不同的时间和加速压力进行注射，这些压力可以单独设置。为了防止用于 TESPEL 加速的高压气体进入 LHD 的真空容器，采用了 3 级差动泵送方案。由于可用空间非常有限，因此每条 TESPEL 注入线都共享 3 级差动泵送系统。出于同样的原因，新 TESPEL 注射系统的一条注射线中的一根导管被故意弯曲（弯曲半径约为 40 m）。新 TESPEL 注射系统的另一条注射线中的导管是直的。我们进行了一项实验室测试，以检查新注射系统中导管的 TESPEL 传输能力。发现 TESPEL 撞击目标箔的点位于由可能的颗粒发散全角 2 度定义的圆圈内。因此，我们确认 TESPEL 可以毫无问题地通过新喷射系统的略微弯曲和直的喷射线。空白喷射测试表明，即使同时使用两条注入管线，总压力的增量也远低于卸货期间 LHD 真空容器的基础压力。这一结果成功地证明了在新注入系统中应用的三级差动泵送方案的能力。