Design studies on a 500 kV DC gun photo-injector for the BXERL test facility

BXERL is a proposal for a test facility (Beijing X-ray Energy Recovery Linac), which requires its injector to provide an electron beam of 5 MeV, 77 pC/ bunch at a repetition rate of 130 MHz (average current of 10 mA). In this paper, we present the design of the injector, which consists of a 500 kV photocathode DC gun equipped with a GaAs cathode preparation device, a 1.3 GHz normal conducting RF buncher, two solenoids, and one cryomodule containing two 1.3 GHz 2-cell superconducting RF cavities as the energy booster. The detailed beam dynamics show that the injector can generate electron bunches with a RMS normalized emittance of 1.49 πmm·mrad, a bunch length of 0.67 mm, a beam energy of 5 MeV and an energy spread of 0.72%.     

BXERL photo-injector based on a 217 MHz normal conducting RF gun

The Beijing X-ray Energy Recovery Linac (BXERL) test facility is proposed in Institute of High Physics (IHEP). In this proposal, the main linac requires the injector to provide an electron beam with 5 MeV energy and 10 mA average current. An injector based on DC gun technology is the first candidate electron source for BXERL. However, the field emission in the DC gun cavity makes it much more difficult to increase the high voltage to more than 500 kV. Another technology based on a 217 MHz normal conducting RF gun is proposed as the backup injector for this test facility. We have designed this RF gun with 2D SUPERFISH code and 3D MICROWAVE STUDIO code. In this paper, we present the optimized design of the gun cavity, the gun RF parameters and the set-up of the whole injector system. The detailed beam dynamics have been done and the simulation results show that the injector can generate electron bunches with RMS normalized emittance 1.0 uppi mmcdotmrad, bunch length 0.77 mm, beam energy 5.0 MeV and energy spread 0.60%.     

Beam dynamics studies of the photo-injector in low-charge operation mode for the ERL test facility at IHEP

The energy recovery linac test facility （ERL-TF）, which is a compact ERL-FEL （free electron laser） two-purpose machine, was proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector that started with a photocathode direct-current gun has been designed. In this paper, optimization of the injector beam dynamics in low-charge operation mode is performed with iterative scans using Impact-T. In addition, the dependencies between the optimized beam quality and the initial offset at cathode and element parameters are, investigated. The tolerance of alignment and rotation errors is also analyzed.     

Beam dynamics studies of the photo-injector in low-charge operation mode for the ERL test facility at IHEP

The energy recovery linac test facility(ERL-TF), which is a compact ERL-FEL(free electron laser)two-purpose machine, was proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector that started with a photocathode direct-current gun has been designed. In this paper, optimization of the injector beam dynamics in low-charge operation mode is performed with iterative scans using Impact-T. In addition, the dependencies between the optimized beam quality and the initial offset at cathode and element parameters are investigated. The tolerance of alignment and rotation errors is also analyzed.     

Design study of a L-band DC photocathode gun

In this paper, we the design study of a L-band DC photocathode gun injector for the ERL (Energy Recovery Linac) test facility. The main parameters of the injector are energy of 2.3 MeV, a bunch length of 2 ps, and a normalized emittance of 2.1 mm.mrad.     

Design study of a L-band DC photocathode gun

In this paper, we the design study of a L-band DC photocathode gun injector for the ERL （Energy Recovery Linac） test facility. The main parameters of the injector are energy of 2.3 MeV, a bunch length of 2 ps, and a normalized emittance of 2.1 mm.mrad.     

Design studies on the ERL-FEL test facility at IHEP, Beijing

A proposed compact ERL test facility at IHEP, Beijing, is presented in this paper, and includes the design parameters, the essential lattice, and the key components features, such as the photocathode DC gun and the CW superconducting accelerating structures. Some important beam physics issues such as the space charge effect, the coherent synchrotron radiation (CSR) effect and the beam break-up (BBU) effect are briefly described with the simulation results.     

Evolutionary genetic optimization of the injector beam dynamics for the ERL test facility at IHEP

The energy recovery linac test facility （ERL-TF）, a compact ERL-FEL （free electron laser） two-purpose machine, has been proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector was designed and preliminarily optimized. In this paper an evolutionary genetic method, non-dominated sorting genetic algorithm II, is applied to optimize the injector beam dynamics, especially in the high-charge operation mode. Study shows that using an incident laser with rms transverse size of 1-1.2 ram, the normalized emittance of the electron beam can be kept below 1 mm.mrad at the end of the injector. This work, together with the previous optimization of the low-charge operation mode by using the iterative scan method, provides guidance and confidence for future construction and commissioning of the ERL-TF injector.     

Design of an electron gun for terahertz radiation source

An EC-ITC(External-Cathode Independently Tunable Cells) RF gun was employed with the aim of obtaining short-pulse bunches with high peak current for a terahertz radiation source. A gridded DC gun plays a key role as the external injecting electron source of the ITC RF gun, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the gridded DC gun should be 15 keV at most. A proper structure of the gridded gun with double-anode is shown to overcome the strong space- charge force on the cathode, which is able to generate 6 μs beam with 4.5 A current successfully.     

砷化镓光阴极直流高压注入器研究进展

主要介绍自由电子激光相干强太赫兹源（FEL-THz）装置上的砷化镓光阴极直流高压注入器的研究进展,并讨论其驱动未来高重复频率短波长自由电子激光器的差距。通过综合砷化镓阴极寿命的三大影响因素,提出了其工作寿命的定性物理模型;通过该模型对阴极和注入器进行优化,在直流高压电子枪上得到了5 mA, 32 min的连续稳定输出;测量了电子束在4.8 mA下归一化发射度约为4.0 mmmrad,阴极热发射度约为0.6 mmmrad,电子束本征横向能量约为92 meV,250 keV电子束在距离阴极90.6 cm处纵向均方根长度约为11.5 ps。这一束流状态已经基本满足FEL-THz需求。     

上海光源150 MeV直线加速器次谐波腔耦合器的设计与调试

通过将次谐波腔体等效为RLC并联回路,求得了射频功率馈入腔体的耦合度公式,分析了上海光源直线加速器次谐波腔输入耦合器的设计要点,通过3维电磁计算软件CST的数值模拟方法对耦合器结构尺寸、耦合环的深度与方位、耦合度进行了模拟计算。介绍了对次谐波腔耦合器进行小信号测试的过程、腔体安装及在线调试的方法。     

上海光源150 MeV直线加速器次谐波腔耦合器的设计与调试

通过将次谐波腔体等效为RLC 并联回路,求得了射频功率馈入腔体的耦合度公式,分析了上海光源直线加速器次谐波腔输入耦合器的设计要点,通过3维电磁计算软件CST的数值模拟方法对耦合器结构尺寸、耦合环的深度与方位、耦合度进行了模拟计算。介绍了对次谐波腔耦合器进行小信号测试的过程、腔体安装及在线调试的方法。     

100kV直流高温超导电缆终端应力锥设计

本文提出了一种新的单直线应力锥设计方法,根据PPLP材料的绝缘特性,结合超导电缆的本体尺寸和设计电压,给出了增饶绝缘厚度和应力锥轴向长度的设计数据,其中增饶绝缘厚度为3.5 mm,应力锥轴向长度为38.5 mm,并对单直线应力锥进行电场数值分析,结果表明,所设计的单直线应力锥满足100 kV直流高温超导电缆运行要求。     

微通道板(MCP)电子清刷用电子枪的设计

为了满足Φ30mm MCP大束流短时间电子清刷新工艺要求，以轴向电子枪工作原理为基础，利用静电场对电子的作用理论，分析了电子的运动轨迹，并对电子的偏转进行了计算。根据计算结果，设计了电子枪的基本结构，确定了电子枪的各种参数：灯丝材料为Φ0.05mm的钨（75%）铼（25%）合金丝；灯丝形状为“∨”字型；电子枪外径为Φ35mm，高度为20mm，最大加热功率为12.6W时，电子发射电流密度达到1.26×10-5A/cm2。用该电子枪对4块性能相近的Φ30mm MCP电子清刷4h后，MCP的增益值达到500±50。这表明：用新电子枪可以代替原RUS-A型电子枪。     

Design study on the merger for BXERL-FEL

In North China, there is a preliminary proposal for ERL-FEL light source (BXERL-FEL) with its aim at "one machine, two purposes" (the XFEL and ERL work simultaneously). One of the key technologies is the merger section. In this paper, we give the physical design of the merger section for BXERL-FEL which merges three kinds of electron beam.     

Design study on the merger for BXERL-FEL

In North China, there is a preliminary proposal for ERL-FEL light source （BXERL-FEL） with its aim at ＂one machine, two purposes＂ （the XFEL and ERL work simultaneously）. One of the key technologies is the merger section. In this paper, we give the physical design of the merger section for BXERL-FEL which merges three kinds of electron beam.     

120 MW束流功率速调管电子枪设计

速调管电子枪是速调管重要部件之一,它为速调管高频腔提供直流电子注。对国产50 MW速调管电子枪束流光学系统进行了模拟分析,并对电子枪陶瓷筒进行了重新设计和优化。为了在国产30 MW速调管的基础上设计50 MW速调管,采用进口钡钨电子枪阴极来减小蒸发和抑制打火,将电子注电压提高到320 kV,电流和导流系数分别为346 A和1.91 μp,以满足速调管功率提高的需要。设计出低电场强度（22.1 kV/mm）电子枪新结构,即在不影响电子枪内部束流稳定的前提下,将陶瓷筒设计成靠近阴极端半径较大而远离阴极端半径较小的形状,以避免高功率运行致使陶瓷筒的损坏。     

BEPCII电子枪系统设计

 BEPCII改进工程需要更高流强的电子枪。新电子枪系统的物理设计、机械设计、控制系统设计等均进行了描述。电子枪的设计发射电流在脉宽为1 ns时大于10 A，重复频率50 Hz。将会采用脉冲电源来为电子枪提供最高200 kV的脉冲高压。在设计阶段，电子枪的几何结构和束流传输过程利用计算机模拟进行了优化。EGUN和DGUN的计算结果表明导流系数为0.22 mA·V^-3/2，电子枪出口的发射度为16 p·mm·mrad。PARMELA的模拟结果表明束流能顺利地传输至第一根加速管末端，捕获效率为67%，出口的均方根发射度为25 mm·mrad。基于EPICS平台的电子枪控制系统设计也已完成，提供了全新的双脉冲运行模式和2.5 μs长脉冲运行模式。     

高功率速调管电子枪热形变分析与测试

国产50 MW速调管需要脉冲功率为120 MW的电子枪,其阴极为皮尔斯型储备式阴极,扫描直径为85 mm。利用ANSYS 对该速调管电子枪的温度场分布及结构的热变形进行了模拟分析。对于电子枪复杂的内部结构形态以及能量转换方式,分析了热传导方式对温度场的影响。在此基础上进行了温度场与结构变形的耦合分析,利用EGUN对电子枪形变前后束流光学特性进行模拟分析,并对模拟结果与高功率测试结果进行了分析比较。     

高功率速调管电子枪热形变分析与测试

 国产50 MW速调管需要脉冲功率为120 MW的电子枪,其阴极为皮尔斯型储备式阴极,扫描直径为85 mm。利用ANSYS 对该速调管电子枪的温度场分布及结构的热变形进行了模拟分析。对于电子枪复杂的内部结构形态以及能量转换方式,分析了热传导方式对温度场的影响。在此基础上进行了温度场与结构变形的耦合分析,利用EGUN对电子枪形变前后束流光学特性进行模拟分析,并对模拟结果与高功率测试结果进行了分析比较。