Secondary electron emission and surface charging evaluation of alumina ceramics and sapphire
Secondary electron emission and surface charging evaluation of alumina ceramics and sapphire
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DOI：
10.1109/tdei.2006.1593403
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发表时间：
2006-02
影响因子：
3.1
通讯作者：
Suharyanto;Y. Yamano;S. Kobayashi;S. Michizono;Y. Saito
中科院分区：
文献类型：
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作者：
Suharyanto;Y. Yamano;S. Kobayashi;S. Michizono;Y. Saito
氧化铝射频窗口的击穿主要是由微放电以及材料缺陷和污染引起的。由于倍增器引起局部表面加热，导致表面熔化，有必要在高温条件下观察氧化铝陶瓷的二次电子发射（SEE）系数。利用扫描电子显微镜（SEM），采用单脉冲电子束（100 pA，1 ms），在室温和650 ℃下测量了工业氧化铝陶瓷和蓝宝石的单粒子效应系数。同时，还对SiO2、MgO等添加剂进行了研究.表面充电评估也变得重要，因为累积的电荷在阈值Held下放电，导致表面放电。表面充电评估进行了多脉冲测量与连续脉冲的样品上的注射。结果，除了蓝宝石之外，证实了SEE系数随温度的降低。多脉冲测量结果表明，蓝宝石的表面充电高于其他样品。与氧化铝陶瓷相比，这可能是导致蓝宝石对于射频窗口应用不耐用的因素之一。虽然有少数例外，但发现氧化铝陶瓷的SEE系数随着纯度和平均晶粒尺寸的增加而增加
The breakdown of alumina rf windows is mostly caused by multipactor, as well as by material defects and contamination. Since multipator induces localized surface heating, leading to surface melting, it is necessary to observe secondary electron emission (SEE) coefficients of alumina ceramics under high temperature conditions. The SEE coefficients of commercial alumina ceramics and sapphire were measured by a scanning electron microscopy (SEM) with a single short-pulsed electron beam (100 pA, 1 ms) at room temperature and at 650degC. Additive materials used for sintering alumina, such as SiO 2 and MgO, were also investigated. Surface charging evaluations have also become important because the accumulated charges are discharged at the threshold Held, resulting in surface discharge. The surface charging evaluations were carried out by multi-pulse measurements with the injection of successive pulses on the sample. As a result, reductions in the SEE coefficients with temperature were confirmed, except for sapphire. The multi-pulse measurement results indicated that surface charging of the sapphire was higher than that of other samples. This may be one of the factors that causes sapphire not to be durable for rf window applications, compared with alumina ceramics. Although there are few exceptions, it was found that the SEE coefficients of alumina ceramics increased with the purity and the average grain size