1. DB Klystron Modulators R&D Status
Dr. Davide Aguglia, TE/EPC
CLIC Project Meeting #12, CERN
24th May 2013
Work Package description & Specifications
R&D strategy and collaborations
Solutions under study
Ongoing work
Preliminary results / Issues
Published results
Planning
Conclusion

2. WP description and specifications
~1600 klystron Modulators required here
Modulator main specifications
Pulse voltage
Vkn
150 kV
Pulse current
Ikn
160 A
Peak power
Pout 24 MW
Rise & fall times
trise 3 μs
Flat-top lenght
tflat
140
Repetition rate
Repr 50 Hz
Flat-top stability
FTS
0.85 %
Pulse repeatability
PPR
10-50
ppm
High efficiency
High reliability / availability
Goal: 2 full scale DB CLIC klystron modulators prototypes in 2016
CERN + External collaborations
ETH Zurich, CH
University of Nottingham, UK
LAVAL University, Canada
DB klystron modulators R&D status

3. R&D strategy and collaborations
General concept
At CERN we study common issues to all R&D partners
Tasks allocation considering partner expertise
Obtain 2 topologically different solutions (VAC not defined)
Low voltage configuration
High voltage configuration
DB klystron modulators R&D status

4. Solutions under study
Basic principles and power fluctuation problematic of klystron modulators
One slowly charges a capacitor bank at low power and discharge it at high power when pulse needed.
Power fluctuation problematic
DB klystron modulators R&D status

5. DB klystron modulators R&D status
Solutions under study
New topologies under study
ETHZ Special spec- Consideration of a DC voltage< 4kV; parallel modularity
LAVAL Special spec- Consideration of a DC voltage> 4kV; series modularity
1. Allows parallel redundancy.
2. use of standard LV switches.
3. Fast voltage rise-time
4. Natural voltage balancing
1. 2-purpose active bouncer: pulsed voltage regulation & constant power consumption
2. Alleviates charger’s spec.
DB klystron modulators R&D status

6. DB klystron modulators R&D status
Ongoing work
ETHZ: 1. Construction of full-scale split-cores HV pulse transformer prototype, 2. Design of multiphase active bouncer.
Uni Nottingham: 1. Evaluation of candidate charger topologies, 2. Optimisation of Grid-layout for CLIC.
LAVAL Uni: 1. HV insulating materials studies (with measurements) 2. HV pulse transformer optimisation, 3. 2-purpuse active bouncer small scale prototype construction.
CERN: 1. Power converters repeatability prediction and measurements techniques 2. High precision and repeatable HV measurement systems.
DB klystron modulators R&D status

7. Preliminary results / Issues
Output voltage pulse feasibility
With the 2 proposed topologies, it seems possible, by numerical simulation, to obtain the required output pulse.
Promising topologies
The 2 topologies (ETHZ - LAVAL) are very promising. Not possible to argue which is best yet.
Prediction on meeting specifications
Pulse shape: Seems possible to meet.
AC power fluctuation: Depends to which extent…specs on 400kV lines under definition! Seems possible to achieve 5% of power fluctuation “easily”.
Pulse to Pulse repeatability: very challenging – Impact on cost if 10ppm - strong collaboration with RF needed.
Electrical efficiency: Probably achievable with a centralised chargers 75MW each)…to early to answer.
DB klystron modulators R&D status

8. DB klystron modulators R&D status
Published results
17 papers (journal and conferences) on novel modulators topologies and design methods
D. Aguglia, P. Viarouge, C. A. Martins, “Frequency-Domain Maximum Likelihood Estimation of High-Voltage Pulse Transformers Models Parameters”, IEEE Transactions on Industry Applications, 2013.
Candolfi, S., D. Aguglia, P. Viarouge, J. Cros, “Efficient parameter identification method for high voltage pulse transformers”, IEEE pulsed power and plasma science conference (PPPS), San Francisco, USA, June 2013.
Candolfi, S., P. Viarouge, D. Aguglia, J. Cros, “Finite elements based optimal design approach for high voltage pulse transformers”, IEEE pulsed power (PPPS), San Francisco, USA, June 2013.
M. Jancovic, A. Watson, J. Clare, P. Wheeler, D. Aguglia, “Grid interface challenges and candidate solutions for the Compact linear collider’s (CLIC) klystron modulators”, IEEE pulsed power (PPPS), San Francisco, USA, June 2013.
F. C. Magallanes, D. Aguglia, P. Viarouge, C. A. Martins, J. Cros, “A novel active bouncer system for klystron modulators with constant AC power consumption”, IEEE pulsed power (PPPS), San Francisco, USA, June 2013.
S. Blume, J. Biela, “Optimal Design Procedure of an Active Bouncer for an Ultra Precise Long Pulse Solid State Modulator”, ”, IEEE pulsed power (PPPS), San Francisco, USA, June 2013.
K. Papastergiou, D. Aguglia, “Power system design compromises for large-Scale linear particle accelerators”, European Power Electronics Conference (EPE), Lille, France, September 2013.
D. Aguglia, M. Neuhaus, “Laminated magnetic materials losses analysis under Non-Sinusoidal Flux Waveforms in Power Electronics Systems”, the European Power Electronics Conference (EPE), Lille, France, September 2013.
DB klystron modulators R&D status

9. DB klystron modulators R&D status
Published results
D. Aguglia, “Pulse Transformers Design for Magnets Powering in Particles Accelerators”, European Power Electronics Conference (EPE), Lille, France, September 2013.
S. Blume D. Gerber J. Biela, Optimal Transformer Design for an Ultra Precise Long Pulse Solid State Modulator, Proceedings of the 4th Euro-Asian Pulsed Power Conference (EAPPC), Karlsruhe, Germany, Sept Oct. 4., 2012.
F. C. Magallanes, D. Aguglia, C. A. Martins, P. Viarouge, “Active damping filter for high bandwidth – low ripple pulsed converters”, 15th International Power Electronics and Motion ontrol Conference, EPE-PEMC, Novi Sad, Serbia, 2012, pp. 1 – 7.
F. C. Magallanes, D. Aguglia, C. A. Martins, P. Viarouge, “Review of design solutions for high performance pulsed power converters”, 15th International Power Electronics and Motion ontrol Conference, EPE-PEMC, Novi Sad, Serbia, 2012, pp. 1 – 6.
D. Aguglia, E. Sklavounou, “ Klystron modulators capacitor chargers design compromises for AC power quality increase of the compact linear collider”, SPEEDAM, Sorrento (IT), 2012, pp. 1 – 7.
R. H. Soares, D. Aguglia, “Pulse-to-pulse reproducibility efficient prediction method for high precision klystron modulator design”, in Proc. IEEE IPMHVC, San Diego (CA), USA, 2012, pp. 1 – 4.
D. Aguglia, P. Viarouge, C. A. Martins, “Frequency domain non-linear identification method for high voltage pulse transformers”, in Proc. International conference on Electrical Machines (ICEM), Marseille, France, 2012, pp. 1 – 7.
P. Viarouge, D. Aguglia, C. A. Martins, J. Cros, “Modeling and dimensioning of high voltage pulse transformers for klystron modulators”, in Proc. International conference on Electrical Machines (ICEM), Marseille, France, 2012, pp. 1 – 7.
D. Aguglia, C. de Almeida Martins, M. Cerqueira Bastos, D. Nisbet, D. Siemaszko, E. Sklavounou, P. Viarouge, “Klystron Modulator Technology Challenges for the Compact Linear Collider (CLIC), In Proc., IEEE International Conference on Pulsed Power, Chicago, 2011.
DB klystron modulators R&D status

10. Planning Planning & collaborations ETHZ LAVAL Nottingham CERN (3 Fell)
Transfo. Design tool +validation & active bouncer
Transfo. Design tool + Validation & novel active bouncer design + small scale validation
Components order & assembly of transfo. + active bouncer
Modular multilevel Converter capabilities study + validation
Repeatability & reliability studies + validation / statistical mes.
2013
Charger studies + validation & component order for full scale
Continuation & input to collaborations
2014
Topology selection & Grid layout optimisation
2015
Mod 1 assembly & tests + control optimisation
Decision on charger for Mod 2
Assembly of PFS at CERN
Standard (industrial) or Nottingham charger construction
Mod 1 delivered to CERN
2016
Mod 2 delivered to CERN
DB klystron modulators R&D status

11. DB klystron modulators R&D status
Conclusion
Work Package mainly keeps the original objectives.
Specifications are very hard to be met – in 2016 there will be 2 modulators respecting at least the pulse shape and stability. We do the maximum to reach the highest repeatability, efficiency, reliability and minimum AC power fluctuation.
A collaborative approach with RF must be adopted regarding repeatability issues.
We are on schedule (for the moment at least).
DB klystron modulators R&D status