BEPCⅡ直线注入器重大改进进展(英文)

Progress of the Injector Linac Upgrade for the BEPCⅡ Project 

BEPCⅡ是“工厂”型的高亮度正负电子对撞机 .它要求其直线注入器提供高能 (1.89GeV)和强流(40mAe+,30 0mAe- )的正负电子束以实现全能量注入和高注入速率 (5 0mA/min .e+) ,并要求直线注入器出口正负电子束的发射度低 (1.6πmm·mrade+,0 2πmm·mrade- )、能散小 (± 0 5 % )以满足储存环接受度的要求 .因此 ,必须对现有BEPC的直线注入器作重大改进 ,包括新电子枪及其束流调整系统、新正电子源及其磁号装置、新微波功率源及其相位控制系统、新的束流轨道和光路调整系统等 .这些新系统和装置大多已完成了设计、研制、测试和试组装等 ,将在今年的春夏安装于隧道 ,并期望在年底前获得正负电子束 .

BEPCⅡ——an upgrade project of Beijing Electron Positron Collider (BEPC) is a factory type of e +e - collider. It requires its injector linac to have a higher beam energy (1.89 GeV) for on-energy injection and a higher beam current (40 mA e + beam) for a higher injection rate ( 50 mA/min). The low beam emittance (1.6π mm·mrad for e + beam, and 0 2π mm·mrad for 300 mA e - beam) and the low beam energy spread (±0 5%) are also required to meet the storage ring acceptance. Thus the original BEPC injector linac must be upgraded to have a new electron gun with its complete tuning system, a new positron source with a flux concentrator, a new RF power system with its phasing loops and a new beam tuning system with orbit correction and optics tuning devices. These new components have been designed, fabricated, tested and will be installed in their final positions in this spring and summer, which are described in this paper.