Medium barrel

The invention provides a medium barrel. The medium barrel comprises a barrel-shaped flow guide structure; the side wall of the barrel-shaped flow guide structure inclines or protrudes inwards, so thatgas flowing into the barrel-shaped flow guide structure can flow close to the inner wall of the barrel-shaped flow guide structure. According to the medium barrel provided by the invention, glow extinction phenomena can be reduced, the stability of plasmas is improved, and therefore, process results are improved. 本发明提供一种介质筒，包括一筒状导流结构，筒状导流结构的侧壁向内倾斜或者凸起，以使流入筒状导流结构的气体能够紧贴筒状导流结构的内壁流动。本发明提供的介质筒，能够减少灭辉现象的产生，提高等离子体的稳定性，从而提高工艺结果。