| 摘要 |
<p>An electron emitter comprises a single, cubic lanthanum hexaboride crystal (1) mounted in a supporting material heatable by heating wires (3), the arrangement being such that a naturally grown edge (2) between two crystal faces, preferably (1,0,0) faces, forms a line emitter which has high length to radius and width ratios, preferably of at least 50 : 1.</p> |
