Development of high-power radio-frequency components for electron-beam feedback and control systems.

下一代正负电子对撞机(如：和x射线光源(如：NLS)。在光束尺寸、轨道和稳定性方面的公差比现有设施大两到三个数量级。例如，在CLIC，光束大约有1纳米高，为了达到希格斯玻色子和超对称物理所需的高亮度，它们必须在相互作用点稳定在亚纳米水平。为了在x射线自由电子激光（XFEL）光源中达到峰值亮度，也必须满足类似的要求。由于这种加速器的束状结构，用于波束轨道稳定的反馈系统必须在1-100纳秒的时间尺度上运行，这是极具挑战性的。纳秒时间尺度反馈（FONT）项目得到了（PPARC和STFC）的支持，以开发用于此目的的低延迟反馈原型。原型已经在SLAC和KEK的光束线中进行了测试，反馈延迟分别在全模拟和数字系统中低至23ns和132ns。我们现在建议将这项技术扩展到前馈系统的开发中，用于校正CLIC驱动梁的纵向相位不稳定性。这种不稳定性为CLIC减速低能量、大电流驱动光束、为高能量、低电流主光束提供高梯度加速度的方法提供了潜在的“阻碍因素”。因此，在未来5年里，开发一种合适的校正系统被列为CLIC研发计划的重中之重，并将于2016年发布技术设计报告。欧洲核子研究中心明确支持牛津约翰亚当斯研究所（JAI）的FONT小组将该系统作为英国/欧洲核子研究中心CLIC研发计划的关键部分。从概念上讲，CLIC前馈系统的许多要求与FONT反馈原型相似：低延迟、高带宽和短时间尺度（数百秒）内的高驱动功率。然而，设计参数要求2.5 GeV驱动光束的动态范围为+-375 urad，带宽为10ns，脉冲长度为240ns。这对驱动放大器系统提出了一个重大挑战。目前的CLIC驱动光束前馈系统概要设计（可能会修改）将需要大约800个放大器，总峰值功率为200兆瓦，估计系统成本约为6000万英镑。这为工业公司参与设计制造所需的先进工程以及由此产生的业务提供了相当大的机会。该学生将与JAI/Oxford FONT小组合作，为前馈系统开发射频（RF）组件。我们建议设计和制造原型放大器元件。初始组件设计将在JAI/Oxford完成。生产设计和制造将由TMD完成。原型将在牛津进行台架测试，然后运往欧洲核子研究中心，安装在CTF3束流线上，用于后续的电子束操作。该学生将与在该领域具有国际知名度的团体合作。JAI/Oxford小组已经在SLAC和KEK开发了用于FONT系统测试的射频设备。这些是世界领先的低延迟波束反馈系统。TMD拥有世界一流的高功率射频器件制造能力和丰富的粒子物理加速器项目经验。项目团队在这一领域有着良好的业绩记录：2004年至2008年期间，JAI/Oxford和TMD（通过CASE学生项目）在KEK的fon4反馈系统的大功率驱动放大器上进行了合作。该团队将提供许多机会，选择和灵活性，以追求硬件开发和射频设计的一般培训。这是一个非常令人兴奋和具有挑战性的项目，对未来大电流驱动束加速器的发展至关重要。

Ultra low-emittance electron beams are required for the next generation of electron-positron colliders (eg. CLIC) and X-ray light sources (eg. NLS). The tolerances on the beam size, orbit and stability are two to three orders of magnitude greater than at current facilities. For example, at CLIC the beams will be roughly 1 nanometre high and they must be stabilised at the sub nanometre level at the interaction point in order to achieve the high luminosity required for Higgs boson and supersymmetry physics. Similar demands must be met to achieve peak brilliance at X-ray free electron laser (XFEL) light sources. Because of the bunch structure of such accelerators a feedback system for beam orbit stabilisation must operate on the 1-100 nanosecond timescale, which is extremely challenging. The Feedback on Nanosecond Timescales (FONT) project has been supported (by PPARC and STFC) to develop low-latency feedback prototypes for this purpose. The prototypes have been tested in beamlines at SLAC and KEK and feedback latencies as low as 23ns and 132ns have been demonstrated with all-analogue, and digital, systems respectively. We now propose to extend this technology to the development of a feed-forward system for correction of longitudinal phase instabilities in the CLIC drive beam. Such instabilities present a potential 'show-stopper' for the CLIC approach of decelerating a low-energy, high-current drive beam to provide high-gradient acceleration to a high-energy, low-current main beam. Therefore, development of an appropriate correction system has been assigned a high priority in the CLIC R&D programme for the next 5 years, leading towards a technical design report in 2016. CERN is explicitly supporting the FONT group at the John Adams Institute (JAI)/ Oxford to work on this system as a key part of the UK/CERN R&D programme on CLIC. Conceptually many of the CLIC feed-forward system demands are similar to those of the FONT feedback prototypes: low latency, high bandwidth and high drive power over short timescales (hundreds of ns). However, the design parameters call for a dynamic range of +-375 urad kick to the 2.5 GeV drive beam, with 10ns bandwidth, and a pulse length of 240ns. This presents a major challenge for the drive amplifier system. The current CLIC drive beam feed-forward system outline design (subject to revision) will require around 800 amplifiers, with a total peak power of 200 MW, and an estimated system cost of around £60M. This presents a considerable opportunity for an industrial company to participate in the advanced engineering required for design for manufacture, and the resulting business. The student will work with the JAI/Oxford FONT group to develop radio frequency (RF) components for the feed-forward system. We propose to design and fabricate prototype amplifier components. Initial component design will be done in JAI/Oxford. Production design and fabrication will be done by TMD. Prototypes will be bench tested in Oxford, and shipped to CERN for installation in the CTF3 beamline for subsequent operations with the electron beam. The student will work with groups that have international profiles in this area. The JAI/Oxford group has developed RF devices for the FONT system tests at SLAC and KEK. These are world-leading low-latency beam feedback systems. TMD has world-class manufacturing capability in high-power RF devices and considerable experience with particle physics accelerator projects. The project team has a demonstrated track record in this area: JAI/Oxford and TMD collaborated between 2004 and 2008 (via a CASE studentship project) on the high-power drive amplifier for the FONT4 feedback system at KEK. The team will provide many opportunities, options and flexibility to pursue development of the hardware and general training in RF design. This is an extremely exciting and challenging project that is vital for the future development of high-current drive-beam accelerators.