| 摘要 |
<p>PURPOSE:To reduce the leakage electron beam by extending while shielding the front face section of a thermal shield between a filament and the tip of a cathode rod. CONSTITUTION:A filament 2 is wound coaxially and spirally around a cathode rod 1 located in a wenelt electrode 4 while a thermal shiled 3 is arranged over the filament 2. Then the front face section 3a of the thermal shield 3 is extended between the tip section 1b of the cathode rod 1 and the filament 2. Consequently the leakage electron beam from the filament can be suppressed.</p> |
