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在一定使用条件下,即使整个阴极有足够的发射,由于阴极表面上形成的高逸出功斑点,仍会导至阴极失效。这种失效在光导授象管使用的氧化物阴极中发现过,该管的电子束电流来自阴极表面的一小部分。利用奥杰电子谱仪和低能电子扫描探针配合等表面分析技术,揭示出高逸出功部分可能是与阴极表面钙的集中度高和钡的集中度低有关。奥杰溅射剖面也说明了,这个钙的富集区域(高逸出功斑点)实际上是厚度为100A数量级的表面簿层。而整个阴极组成是均匀的。这些斑点可能是BaO与BaCO_8转化的低共熔过程中产生的CaO熔渣。
Under certain conditions of use, even if the entire cathode has sufficient emission, the cathode will still fail due to the high work function spot formed on the cathode surface. This failure was found in the oxide cathode used in the light guide tube, which has a beam current from a small portion of the cathode surface. Using surface analysis techniques such as Aojie electron spectroscopy and low energy electron scanning probe, it is revealed that the high work function may be related to the high concentration of calcium on the cathode surface and the low concentration of barium. The Oerlikon sputtering profile also shows that this calcium-rich region (high work function spot) is actually a surface finish of the order of 100A in thickness. The entire cathode composition is uniform. These spots may be the CaO slag generated during the eutectic transformation of BaO with BaCO_8.