Development of Multibunch Beam Energy Compensation System

多束团能量补偿方法的研究是直线对撞机发展的关键技术之一，在高能加速器研究机构ATF（Accelerator Test Facility）进行。中频相位调制法是目前最可行的多束团能量补偿方法，为此进行了应用该方法的发展性研究。1997年，即本课题研究的第一年，完成了大功率中频合路器的设计和制作，实现了两个速调管输出功率的联合收割机，中频合成器的大功率试验是在ATF速调管系统上进行的，采用了波导系统的重新组合，实现了两个速调管输出的联合收割机合成。该系统在50 MW速调管输出水平上进行了调试，验证了其在大功率水平上的相幅调制性能。相位调制控制脉冲中装有任意波形发生器。在ATE直线加速器中，超导磁体结构安装在加速器的中间，用于多束团能量测量。为了优化中频幅值变化斜率，测量了各速调管在低中频下的相位调制速度，并通过调整，成功地补偿了ATE多聚束（20聚束，2.8ns间距）的束流能量差。本实验证明了相位-振幅调制法对多束团能量补偿的适用性，经过两年的研究，使相位-振幅调制法对多束团能量差补偿成为可能，这将是未来直线对撞机的一个难题。同时也可以知道在真实的应用中需要开发的if组件。

The development of multibunch beam energy compensation method is held in ATF(Accelerator Test Facility) of the high energy accelerator research organization as an one of key technology of linear collider developments. The if phase modulation method for multibunch energy compensation is the most feasible method, so the development research to apply this method was proceeded. It is possible to reduce the emittance growth arising from the effect of dispersion and chromatic effect to its minimum, because of structure by structure of energy compensation.In 1997, the first year of this reseach, the design and fabrication of the high power if combiner to combine the output power of two klystrons were done, The high power test of the if combiner was held at ATF klystron system with rearranged wave guide system in order to combine two klystrons output. The system was processed upto 50MW klystron output level and proved the performance of phase-to-amplitude modulation at high power level.In 1998, the second year, the beam test was held at ATE linac. The arbitoraly waveform generator is installed in the phase moduration control pulse. In ATE linac, the sichane magnet configuration is install in the middle of linac in oider to make multibunch energy measurement. In order to optimize the if amplitude variation slope, the phase moduration speed at low-level if for each klystron was surveyed, By using these instruments and careful adjustment, we could succeed to compensate the beam energy difference in ATE multibunch (20 bunch, 2.8ns spacing). This experiment proved that the phase-to amplitude moduration method is applicable for the multibunch energy compensation.This two years research makes it possible that the phase-to-amplitude moduration method is effective to compensate multibunch energy difference which will be a problem in future linear collider. Also we could know the if component which is need to develop for real application.