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

2. 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

3. 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

4. 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

5. 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

6. 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

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

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

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

10. 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.

11. 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

12. 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

13. 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]