(西安交通大學(xué) 理學(xué)院，西安 710049)
摘 要: 采用掃描電子顯微鏡觀察了納晶結(jié)構(gòu)和粗晶結(jié)構(gòu)的W-20%Cu和Cu的首擊穿燒蝕形貌，指出納晶電弧燒蝕痕跡分散，燒蝕比較輕微；常規(guī)材料燒蝕比較集中，且燒蝕比較嚴(yán)重。通過(guò)分析陰極材料的微觀結(jié)構(gòu)，建立了多晶材料電子所處勢(shì)場(chǎng)結(jié)構(gòu)模型，通過(guò)數(shù)值計(jì)算得出：晶粒越小，對(duì)應(yīng)價(jià)電子子能帶間能隙越大。分析認(rèn)為，納米晶結(jié)構(gòu)的陰極材料電弧分散是由于較大的能隙阻礙了大量電子同時(shí)參與導(dǎo)電并迫使陰極斑點(diǎn)快速運(yùn)動(dòng)，從而避免大電流產(chǎn)生的焦耳熱所導(dǎo)致的嚴(yán)重?zé)g。
關(guān)鍵字: 納米材料；燒蝕；子能帶；Kronig-Penney模型
nanocrystalline cathode materials
（School of Science, Xi’an Jiaotong University, Xi’an 710049, China）
Abstract:The arc tracks on the conventional and nanostructured W-20%Cu and Cu after the first discharge were investigated by scanning electron microscopy. It is found that for the nanostructured cathodes, the erosion is slight and spreads over a dispersal area, while for the conventional cathodes, the erosion locates intensively at some specifically area. A simple model potential was built through analyzing the microstructure of the cathodes. The computational results show that the subband gap is wider for the nanostructured cathodes than for those of the conventional cathodes. It is the relatively wide energy gaps in the nanostructured cathode materials that clag electrons movement between the potential barriers and force cathode spots move quickly from one site to another, which in return avoids very high-current and severe cathode erosion.
Key words: nanostructured materials; erosion; subband; Kronig-Penney model
