UK X FEL Kick-off Meeting A Moss on behalf of A Wheelhouse ASTeC, STFC Daresbury Laboratory WP2 - RF Development 4th July 2017

Outline Objectives Task 2.1: Frequency Options Task 2.2: LLRF Development Future Plans Task 2.3: Modulator Technology Task 2.4: Cavity Optimisation Deliverables & Milestones

Objectives The motivation of this WP is to address the RF technology challenges faced for the design of a UK X-FEL to deliver high stability and high reliable accelerator. To meet these demands it will be necessary to improve upon existing technologies to meet the high stability requirements:- Amplifier systems and/or High power modulators Low level RF (LLRF) systems It will necessary to analyse and understand the pros and cons between normal conducting and superconducting systems in terms of running costs and performance. It will be necessary to define a suitable operating (or suitable operating frequencies) for the machine An assessment of the available RF technologies The associated costs

Task 2.1: Frequency Options C Christou, A. Wheelhouse, G. Burt, R. Jones Task Aims:-  Assessment of normal and super-conducting options Linked with accelerator design options Review of the available RF amplifier sources - Determining frequency, peak and average power capabilities, and costs (including associated costs) Review of high gradient accelerating structures to understand Achievable gradients, Beam-loading effects, Breakdown rates, Beam quality preservation Define Operating frequency / frequencies Repetition rate options (or CW) for the machine Evaluation of costs Build costs Operating costs

Task 2.1: Frequency Options Assessment of normal and super-conducting options Normal conducting S, C or X-band or combination Super-conducting Improvements made in Gradients Q Cheaper operating costs Accelerator options Linear ERL

Task 2.2: LLRF Development A. Moss, K. Dumbell, E-F. Palade, A. Dexter Task Aims:- Perform measurements on the existing CLARA systems to benchmark the capability of existing LLRF systems. Develop further LLRF systems hardware and software to improve upon stability. Potential assessment of hybrid digital and analogue system. Development of a self-calibration system to provide improved stability Evaluation of the DESY system. Short pulse versus long pulse feedback/feedforward

LLRF hardware DL designed LLRF prototype being used for ESS cavity testing DESY mTCA digitiser Commercial LLRF system

Measurement's performed on current hardware Additive Phase noise measurement of an amplifier Working with manufacturer to improve results Understand were our limitations are

Measurement's continued Pulse analysis of amplifier systems Will extend testing on to modulators and higher power amplifier's

Task 2.3: Modulator Technology S. Griffiths, C. White, T. Hartnett, A. Moss Short pulse Task Aims:-   Perform measurements on the existing CLARA RF systems to benchmark the capability of existing systems. Engage with modulator firms to work with them to improve the critical parameters which effect the synchronisation and the stability of the accelerator Engage with solid state amplifier companies to assess the capability of improving phase and amplitude stability of their amplifiers.

Task 2.3: Modulator Technology Diversified Technologies ScandiNova Ampegon Major source of instabilities:- Amplitude and phase CLARA requirement 0.1%, 0.1⁰ Pulse repeatability and reproducibility Timing jitter

Task 2.4: Cavity Optimisation G. Burt, R. Jones, L. Cowie, P. Goudket Task Aims:-   Follow on from the review of high gradient accelerating structures (from Task 2.1) to gain a better understanding of the requirements Design optimization study – Sensitivity studies. Understanding of alignment requirements Review of emittance growth with respect to tolerances Beam instabilities Multi-bunch capabilities Short-range wakefield effects CSR emissions

Deliverables & Milestones Del 2.1 Report on available RF sources with a cost analysis. [M12] Del 2.2 Report on a review of normal conducting versus superconducting RF. [M6] Del 2.3 Report on high gradient accelerating structures. [M18] Del 2.4 Report on frequency options. [M24] Del 2.5 Report on the CLARA LLRF performance. [M24] Del 2.6 Report on potential LLRF development options. [M24] Del 2.7 Test and evaluation of new LLRF systems. [M48] Del 2.8 Evaluation of the DESY calibration system. [M36] Del 2.9 Report on stability performance of CLARA RF systems. [M18] Del 2.10 Report on opportunities to improve modulator designs capable of providing improved phase and amplitude stability. [M48] Del 2.11 Report on opportunities to improve solid state amplifier designs capable of providing improved phase and amplitude stability. [M36]  Del 2.12 Report on cavity sensitivity studies. [M36] Del 2.13 Report on cavity multi-bunch capabilities. [M48] Del 2.14 Report on cavity Short-range wakefield studies. [M36]