| 摘要 |
<p>PURPOSE:To improve reliability by virtue of strong welding points between a cathode sleeve and a cathode support not to be embrittled at a high temperature by making the part including welding points between the cathode support and the sleeve of a multilayer laminated plate, a clad metal of a chrome-based alloy and nickel, in the state where the chrome-based alloy surface is made to face and the cathode sleeve tantalum surface. CONSTITUTION:A sleeve 3, a cup 2, and a cathode base 1 are welded at three places at intervals of 120 deg. irradiated by a laser beam from the side direction after the cathode base is housed in the cup 2 of tantalum and engaged into the top of the sleeve 3. A cathode support 5 is formed by press working of a clad metal of nichrome (18Cr-Ni)- nickel-nichrome(18Cr-Ni), and the thickness of a nickel layer 9 and a nichrome layer 8 of the clad metal is made to 0.75 mm and 0.925 mm respectively. The sleeve 3 is fixed to the cathode support 5 by laser welding at plural welding points in the vicinity of a bottom so as to be coaxial, and made to be a impregnate type cathode body structure. An almina insulation coating is applied to a heater 4 on its tungsten line surface and the heater 4 is inserted into the sleeve 3. This enables welding parts between the sleeve and the cathode support to almost eliminate an embrittled layer.</p> |
