本文選題：場發(fā)射陰極　切入點：多晶六硼化鑭(LaB6)　出處：《電子科技大學》2015年碩士論文

【摘要】：在各種高能加速器和高頻微波器件等設(shè)備中,常常需要性能優(yōu)良的陰極材料提供亮度高、品質(zhì)好、電流密度大的電子束。與熱陰極相比,場發(fā)射陰極具有不需要加熱、啟動快、脈沖發(fā)射電流密度大等很多優(yōu)點、是電真空器件和各種高能加速器的理想電子源,近年來已成為國內(nèi)外研究的熱點。在各種陰極材料中,LaB6具有優(yōu)異的場發(fā)射性能,但由于其熔點高、化學穩(wěn)定性好,如何設(shè)計場發(fā)射陰極結(jié)構(gòu)和制作成為十分關(guān)鍵的問題。為了提高場發(fā)射陰極的發(fā)射能力,本文設(shè)計并制備了兩種結(jié)構(gòu)(環(huán)狀結(jié)構(gòu)和梳狀結(jié)構(gòu))的多晶LaB6場發(fā)射陰極,通過調(diào)整各項工藝參數(shù),成功制作出一種電子發(fā)射性能優(yōu)良的大面積多晶LaB6場發(fā)射陰極。論文主要研究內(nèi)容包括:1、采用MAGIC軟件模擬計算得出,改變發(fā)射體結(jié)構(gòu)參數(shù)可以提高其表面場強,為后續(xù)制備工作的進行提供了理論基礎(chǔ)。研究得出發(fā)射體結(jié)構(gòu)和發(fā)射材料逸出功是影響陰極場發(fā)射能力的關(guān)鍵參數(shù)。逸出功越低的場發(fā)射材料,其場發(fā)射性能越好。2、采用射頻磁控濺射法在基片表面沉積氮化硅保護層。研究得出隨著射頻功率的增加,沉積速率先增加后減小,同時沉積速率與薄膜的均勻性成反比關(guān)系。工作氣壓越高,薄膜沉積速率越低,而且兩者成線性關(guān)系。3、采用電化學刻蝕法制備多晶LaB6場發(fā)射陰極。研究得出電解液成分、濃度、緩蝕液、水溶劑和極間電壓對發(fā)射體刻蝕形貌的影響。與磷酸相比,鹽酸更適合作為多晶LaB6電化學刻蝕的電解液。在電解液中,緩蝕液的比例越高,發(fā)射體表面越平整;水溶劑含量越低,發(fā)射體表面越粗糙,刻蝕速率越快。4、研究出了一種適合環(huán)狀結(jié)構(gòu)多晶LaB6場發(fā)射陰極的電化學刻蝕方法,其最佳制備參數(shù)為:采用光刻膠作為保護層,基底活化溫度為180℃,時間為3h;電解液配比為V(HCl):V(C2H5OH):V(H2O)=1mL:20mL:20mL,極間電壓為3V,電化學刻蝕時間為1h。最終成功制備出環(huán)狀多晶LaB6場致發(fā)射陰極。5、自行設(shè)計搭建了測試夾具和測試裝置,并對制備出的場發(fā)射陰極進行性能測試。其中,梳狀結(jié)構(gòu)的場發(fā)射陰極發(fā)射性能優(yōu)于環(huán)狀結(jié)構(gòu)。梳狀結(jié)構(gòu)的開啟電場為6~8V/μm,閾值電場為18~21V/μm。經(jīng)測試,多晶材料在低真空下仍然表現(xiàn)出較好的穩(wěn)定性與抗中毒能力,表現(xiàn)出LaB6作為場發(fā)射材料的優(yōu)越特性。
[Abstract]:In various equipment such as high energy accelerator and high frequency microwave device, high performance cathode material is often needed to provide electron beam with high brightness, good quality and high current density. Pulse emission with high current density is an ideal electron source for electric vacuum devices and various high energy accelerators. In recent years, it has become a hot research topic at home and abroad. In all kinds of cathode materials, LaB6 has excellent field emission performance. However, due to its high melting point and good chemical stability, how to design the structure and manufacture of the field emission cathode becomes a key problem. In this paper, two kinds of polycrystalline LaB6 field emission cathodes (ring structure and comb structure) are designed and fabricated. A large area polycrystalline LaB6 field emission cathode with excellent electron emission performance has been successfully fabricated. The main research contents include: 1. The surface field strength can be improved by changing the structure parameters of the emitter by using MAGIC software. The results show that the structure of emitters and the escape work of emitters are the key parameters affecting the field emission ability of the cathode. The better the field emission property is, the better the RF magnetron sputtering method is used to deposit silicon nitride protective layer on the substrate surface. It is found that the deposition rate increases first and then decreases with the increase of RF power. At the same time, the deposition rate is inversely proportional to the homogeneity of the film. The higher the working pressure, the lower the deposition rate and the linear relationship between them. The polycrystalline LaB6 field emission cathode is prepared by electrochemical etching. The composition and concentration of electrolyte are obtained. Compared with phosphoric acid, hydrochloric acid is more suitable as electrolyte for electrochemical etching of polycrystalline LaB6. The lower the content of water solvent, the rougher the surface of emitter and the faster the etching rate. A new electrochemical etching method suitable for annular polycrystalline LaB6 field emission cathode is developed. The optimum preparation parameters are as follows: photoresist is used as protective layer. The substrate activation temperature is 180 鈩，

本文編號：1686717