1. Summary on WG 2
LINAC Technology

2. Discussion on Technical issues
Definition of work package leaders
Work package leaders will be contacted by L. Lilje next week
Lutz Lilje DESY

3. Program
Danilo Barni Module, Tuner (20 min)
AFTERNOON session (Coffe Break 16.00)
Add. information available on request by:
Leaks in tests - Detlef Reschke
Cleanroom Quality control - Axel Matheisen
Flange designs - Kirsten Zapfe
Coupler Design and Processing - Terry Garvey / W.-D. Moeller
HOM and Pickup - Wolf-Dietrich Moeller
Experience Module Assembly Rolf Lange
Active tuning - Lutz Lilje/Stefan Simrock
Priority and effort estimation, definition of Work packages
Presentation of itemized priority list - L.Lilje / D.Reschke (20 min)
Discussion on estimation of the effort needed to address technical issues and priority ranking
Definition of Work packages
Discussion : Distribution of Work packages
Preparation of the Summary
MORNING session
R&D Session
H. Padamsee DESY EP single cell cavity sent to Cornell - various treatments and results – (20min)
H. Padamsee 550 RRR russian Nb single cell cavity high gradients results with thermometry– (20min)
L. Lilje High gradients in TESLA nine-cell cavities – (20min)
General Talk (coffee break)
Paolo Pierini - Design consideration for accelerator reliability (30 min)
Cristian Magne Cold BPM - (30 min)
Overview technical issues related to superconducting accelerating modules
Lutz Lilje String, Cavities, Coupler, HOM , Clean room assembly - (40 min)
Lutz Lilje DESY

4. L. Lilje
High power test
Piezo compensation
Lutz Lilje DESY

5. High Power Test of an EP nine-cell cavity
Calib. Measurement
HERA plant
High Power Test of an EP nine-cell cavity
5 Hz, 500 us fill, 800us flat-top
Feed-forward only
No piezo compensation at the moment
33-35 MV/m with no interruption related to cavity-coupler-klystron since more than 130 hours
2 cryo problems at 95 and 130 hours resulting from connection to the HERA plant
Cryo shutdown right now due to problem of impurities in He circuit (from HERA plant)
(scheduled calibration measurement at 65 hours shown in the plot)
Very low activity in the high power coupler, temperature levels o.k. for 5 Hz
No field emission observable
Lutz Lilje DESY

6. Frequency stabilization at 35 MV/m
Blue: With piezo
Red: Without piezo
Frequency detuning of ~1000 Hz compensated with resonant excitation of a mechanical cavity resonance at 230 Hz.
NOTE: This is rather an demonstration of the capability of active tuning. Application in a real machine is probably difficult/impossible.
Lutz Lilje DESY

7. Hassan Padamsee RF Critical field of niobium ‘In-situ’ Bakeout
Lutz Lilje DESY

8. Lutz Lilje DESY

9. Cornell Results
Lutz Lilje DESY

10. P. Pierini
Reliability
Bottom-up approach is more reasonable than Top-down (complexity generates wrong results)
Lutz Lilje DESY

11. Warning/2
Formal mathematical and statistical methods can be applied to measure and assess reliability characteristics of components, but the associated uncertainties are high, leading to reliability estimates with limited credibility
“(...) the role of mathematical and statistical methods in reliability engineering is limited, and appreciation of the uncertainty is important in order to minimize the chances of performing inappropriate analysis and of generating misleading results. (…) practical engineering must take precedence in determining the causes of problems and their solutions” [PDT O’Connor]
11/19/2018
Lutz Lilje DESY

12. However… There exist design principles to achieve a reliable system:
Derating: Operate components below max rating
Redundancy: Provide more components with a given function
Fault Tolerance: Component failure do not imply system failure
Mathematical and statistical methods for reliability assessment teach us that the reliability of a complex system depends
not only by the component specifications (MTBF/MTTR),
but also, even more importantly, by the logical and functional connections (role of redundancies and spares)
In other words, proper planning of redundancies allows building reliable systems out of moderately reliable components
11/19/2018
Lutz Lilje DESY

13. C. Magne Cold BPM design Dark current monitor
Resolution needed for cavity dark current 100 nA?
Lutz Lilje DESY

14. Cold BPM for TTF2 Tesla prototype
- low beam impedance
cooling to 2K without strain
- Low beam coupling impedance: reduces the beam break-up forces and minimizes the cryogenic heat-load due to resonances.
- The (axial) geometry is favorable to cooling to 2K without strain.
- The dimensions are small.
- The design is adapted to UHV dust-free conditions.
- The mechanics is relatively simple to machine (latheprecision of axial sym.)
Ability to measure sum signal and dark current
Lutz Lilje DESY

15. Dark Current Monitor – laboratory test
Fmono= 1.3 GHz
Fdip = 2.6 GHz
An aluminium prototype has been fabricated to study the optimum antenna design.
- Network analyser
- testbench
Alu prototype
Electronics (analog):
- One unit (refurbished) is avalaible
- Need to build 1 (or 2?) more
Lutz Lilje DESY

16. Discussion on technical issues
Leaks in tests - Detlef Reschke
Flange designs - Kirsten Zapfe
Cleanroom Quality control - Axel Matheisen
Coupler Design and Processing - Terry Garvey / W.-D. Moeller
HOM and Pickup - Wolf-Dietrich Moeller
Experience Module Assembly Rolf Lange
Active tuning - Lutz Lilje/Stefan Simrock
TESLA MEETING May 2003 Frascati
LINAC TECHNOLOGY WORKING GROUP

17. Work package list
Lutz Lilje DESY

18. Work group leader tasks
Initiate decision-making process
Make a detailed list/ programme as soon as possible
Estimation of time required and effort to do this (money, manpower)
List of open questions
Prepare status report for end of August
Report will be made available preferrable through EDMS (Instructions will be send by Axel Matheisen asap)
Discussion during next TESLA Meeting
Lutz Lilje DESY

19. Thanks to all contributors for the very useful discussion and the will to take over the work !!!!
Lutz Lilje DESY