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铁电体阴极的发射性能

EMISSION PERFORMANCE OF FERROELECTRIC CATHODES
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摘要 研究了不同铁电体阴极样品的发射行为表明在同样激励条件下,不同材料的铁电样品发射电流密度有显著差别,在集电极接地情况下,PLZT2/95/5陶瓷测得的最大发射电流密度为35A/cm_2,透明的LiNbO_3单晶为38A/cm_2。样品的击穿阈值是极化难以达到完全翻转的主要障碍。分析了阴极表面金属栅的存在对铁电体发射的不利影响,“E⊥P”激励模式是克服这些困难的一个新途径。对两种最近试制的材料作了发射试验,观测到的最大发射电流密度超过了100A/cm ̄2,估算该发射束的归一化均方根发射度为10 ̄(-6)m·rad和归一化峰值亮度为10 ̄(12)A/m ̄2·rad ̄2量级。 AbstractFerroelectric cathode is a novel high brightness,intense electron beam source. Generally,produce of the electrons is attributed to fast polarization change in ferroelectric samples.Our ex-perimental apparatus consists of a vacuum diode and a 30kV,75Ω,100ns(FWHM)pulser.Wehave ekcentally observed pulsed emission behaviours for a series of ferroelectric samples,The re-sults show that the emitting current measured from varied FE sample have obviously a quantita-tive difference,for example,when anode is grounded,the maximum current density measured is20A/cm ̄2 for PZT-95/5and 38A/cm ̄2 for LiNb_2O_3 monocrystalline. The breakdown threshold ofsample is a primal obstacle which makes polarization difflcult to reverse fully.The metal gride atthe surface of cathode has at least three disfavour factors for ferroelectric emitting:(a)emittingarea of the cathode can not be fully exploited.(b)a part of electrons emitted would return to thegride electrode and can’t be drawn out and used,(c)electric field concentrated on gride stripedge easily causes bulk breakdown of the sample. In order to overcome these difficulties a novelexciting mode,“E⊥P”,have been proposed. Some new ferroelectric samples,which are recently trial-produced,are also tested.Theirmaximum emitting current densities are over 100A/cm ̄2.Normalized emittance and brightnessofthe emitting beam are estimated to be on the order of 10 ̄(-6)m· rad and 10 ̄(12)A/m ̄2· rad ̄2respectively.
出处 《强激光与粒子束》 EI CAS CSCD 1995年第1期75-80,共6页 High Power Laser and Particle Beams
基金 中国国家自然科学基金和中国工程物理研究院科学基金
关键词 铁电体阴极 高亮度电子束源 发射性能 Electron emission Electrooptical effects Ferroelectric materials Laser accessories Polarization
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