Target head reducing device used for sputtering film-coating for interior of tubule

The utility model relates to a target head reducing device used for sputtering film-coating for the interior of a tubule. The device consists of an extension cathode (7), an insulation sleeve (8), an extension shielding sleeve (9) and a small target piece (10), wherein the extension cathode (7) is compressed and fixed on the cathode of a conventional target head by a target piece compression ring (6), the insulation sleeve (8) is arranged outside the extension cathode (7), the extension shielding sleeve (9) is compressed and fixed on the insulation sleeve (8) by a shielding cover (3), and the small target piece (10) is stuck on the end surface of the extension cathode (7) by conduction glue. The target head reducing device can realize sputtering film-coating on the inner wall and the bottom of the tubule; the reducing device for a target head with the needed diameter can be installed on the conventional target head conveniently when in sputtering film-coating; moreover, a vacuum sealing structure is not neede