【摘要】：隨著新型太赫茲器件的迅速發(fā)展,陰極的發(fā)射性能需要達到40-100A/cm2。這一性能指標(biāo)幾乎已達到傳統(tǒng)覆膜浸漬擴散陰極的性能極限。在現(xiàn)有的各種陰極類型中,含鈧擴散陰極具有很高的發(fā)射水平,是最有可能達到新型太赫茲器件要求的陰極。本文研制了一種新型浸漬擴散陰極,所用浸漬活性物質(zhì)的特點是,在鋁酸鹽活性物質(zhì)的基礎(chǔ)上首次同時引入Sr0和Sc203；新陰極的電子發(fā)射性能達到了172A/cm2。此外,本文還對陰極的蒸發(fā)速率及壽命進行了測試,并對陰極表面作了納米掃描俄歇掃描分析。獲得的主要結(jié)論如下： 1.對陰極基體—鎢海綿體進行了研究。一開始我們采用粒徑30-60nm的鎢粉來制備鎢海綿體,但發(fā)現(xiàn),采用模壓或等靜壓成型后,進行高溫浸漬得到的浸漬度明顯偏低(4%左右)；將鎢粉和發(fā)射物質(zhì)按重量比混合壓制成型之后再高溫?zé)Y(jié),很難獲得成形良好的發(fā)射體；最后我們采用3-4pm的分級鎢粉和傳統(tǒng)制備工藝,獲得了孔度為20%-25%、孔隙分布均勻的鎢海綿體,采用這一鎢海綿體浸漬鋁酸鹽,可獲得6.5-7.2%的浸漬度,可較好地滿足陰極對活性物質(zhì)浸漬度的要求。 2.設(shè)計了新的活性物質(zhì)(Ba-Sr-Sc-Al-Ca-O)成分系統(tǒng)。在傳統(tǒng)鋁酸鹽基礎(chǔ)上,首次同時引入SrO和Sc2O3。實驗表明,優(yōu)化SrO和Sc203比例可使陰極獲得優(yōu)異的電子發(fā)射能力。采用26BaO·29SrO·8Sc203·7CaO·Al203配方的新型活性物質(zhì)浸漬的陰極,在1100℃,脈沖發(fā)射電流密度達到172A/cm2,遠(yuǎn)高于傳統(tǒng)M型陰極的發(fā)射電流密度。實驗還測量了陰極的欠熱曲線和功函數(shù),測量及分析結(jié)果表明,新陰極具有良好的電子發(fā)射均勻性。 3.利用納米掃描俄歇顯微鏡等表面分析手段對新陰極表面原子層成分分布進行了分析。結(jié)果顯示,新陰極表面均勻覆蓋了高濃度的Ba、Sc和O的原子層,Ba：Sc元素之比與文獻中獲得最佳發(fā)射的成分比例相一致。 4.研制了滿足太赫茲器件要求的微型帶狀注陰極。帶狀注陰極設(shè)計要求：尺寸為1mmx0.3mm,發(fā)射性能達到50A/cm2。我們采用在圓端面上構(gòu)造小矩形的方法來制備微型帶狀注陰極。矩形以外的部分覆蓋鉬硅化合物薄膜以抑制電子發(fā)射。將陰極裝入太赫茲器件進行了發(fā)射測試,在300μs,20Hz的工作條件下,陰極工作溫度為1080℃,實測發(fā)射電流密度達到了80A/Cm2。
[Abstract]:With the rapid development of new terahertz devices, the emission performance of the cathode needs to reach 40-100A / cm ~ 2. This performance index has almost reached the performance limit of the traditional coated impregnated diffusion cathode. Among the existing cathodes, the Scandium-containing diffusion cathode has a high emission level and is the most likely cathode to meet the requirements of new terahertz devices. A new impregnated diffusion cathode has been developed in this paper. The characteristic of the impregnated active material is that the electron emission properties of the new cathode Sr0 and Sc203; are 172A / cm ~ 2 for the first time on the basis of aluminate active material. In addition, the evaporation rate and lifetime of the cathode were measured, and the surface of the cathode was analyzed by nano-scanning Auger scanning. The main conclusions are as follows: 1. The cathodic matrix tungsten cavernous was studied. At first, we used tungsten powder with particle size of 30-60nm to prepare tungsten sponge, but it was found that the impregnation degree of high temperature impregnation was obviously lower (about 4%) after molding or isostatic pressing. It is difficult to obtain a well-formed emitter when tungsten powder and emitter are mixed and pressed according to weight ratio and then sintered at high temperature. Finally, by using the 3-4pm graded tungsten powder and the traditional preparation process, the tungsten sponge with a porosity of 20-25 and a uniform pore distribution is obtained. By impregnating the aluminate with this tungsten sponge, the impregnation degree of 6.5-7.2% can be obtained. It can meet the requirements of the cathodic impregnation degree of active substances. 2. A new active substance (Ba-Sr-Sc-Al-Ca-O) composition system was designed. On the basis of traditional aluminate, SrO and Sc2O3. are introduced simultaneously for the first time. The experiments show that the cathode can obtain excellent electron emission ability by optimizing the ratio of SrO and Sc203. At 1100 鈩，

本文編號：2397065