1. AB-RF-FB section meeting
PS TFB
PS TFB
Project triggered by: K. Schindl and R. Cappi
Hardware: J. Belleman, A. Blas, T. Bohl, F. Caspers, J.L. Gonzalez, W. Hofle, J. M. Lacroix,
S. Livesley, R. Louwerse, M. Paoluzzi, F. Pedersen, V. Rossi, J. Sladen
Hardware simulations: V. Vendramini, E. Vogel Beam decoherence study: E. Benedetto, M. Chanel, M. Martini, E. Metral, F. Zimmermann
Where do we come from?
Where are we?
Where do we go?
A.B February 2005
AB-RF-FB section meeting

2. AB-RF-FB section meeting
PS TFB
History
05/98 First meeting, start of the PS TFB project
10/98 Start study of a kicker prototype (J-L Gonzalez)
06/99 H Kicker mechanical design started (J-M Roux)
11/99 Mechanical drawings in the final version.
01/00 Price Enquiry for a single bloc vacuum chamber (3 pieces; H + V + spare)
04/00 Second price enquiry sent for vacuum pipes in two pieces (no response for single bloc)
10/00 Order placed to Metaceram (Hiperceramics was second)
05/02 Order cancelled
08/02 New price inquiry
10/02 Order placed to Hiperceramics; delivery planned for April 2003
01/03 Project taken over by rf
10/03 Successful test of electronic prototype on old kicker an amplifier
11/03 Delivery of ceramic pipes
01/04 H kicker Delivered, Ceramic pipe not vacuum tight after brazing (weak metallization)
08/04 Re-design of transition pieces
10/04 Order placed for re-metallization (SCT) and new ceramic rings (Hiperceramics)
A.B February 2005
AB-RF-FB section meeting

3. AB-RF-FB section meeting
PS TFB 1 2 3
A.B February 2005
AB-RF-FB section meeting

4. AB-RF-FB section meeting
PS TFB
Kickers
Initial requirements: R. Cappi 1999
Damping of a +/-1.5 mm oscillation within 100 turns (chromaticity)
Bandwidth: [10kHz - 20 MHz] (q = 0.1, 20 MHz kicker ripple)
Decision taken
2 x 3 kW, magnetic kicker
Final result (F. Caspers 12/04)
Usable bandwidth = 10 MHz (limited by non linear phase and transit time factor (68 ns)
Field above Roberto’s specs (factor 7)
A.B February 2005
AB-RF-FB section meeting

5. AB-RF-FB section meeting
PS TFB
Kickers
Workload for modifying the magnetic kicker?
make it shorter (1/3) for transit time factor
Change the shape of capacitive plate to increase ZC
This means a complete re-design
Could we use the old strip line kicker?
yes!! (see next slide)
A.B February 2005
AB-RF-FB section meeting

6. AB-RF-FB section meeting
PS TFB
Kickers
Why is the strip line kicker ok for the job?
with 2 x 3 kW, it give almost exactly what is required in term of kick
Its bandwidth is only limited by the transit time factor of 3 ns (166 MHz)
What ‘s wrong with it?
Impedance matching to be improved
Impedance transformer required with present amplifiers
From Reinier
Input impedance: 12.5 Ω
Output impedance: Ω (x9)
Each coax: 37.5 Ω = two 75 Ω in //
Voltage gain = 3
A.B February 2005
AB-RF-FB section meeting

7. AB-RF-FB section meeting
PS TFB
Kickers
Is there a security margin with the strip line kicker?
The LHC beams have been obtained without dampers 
Factor 6.25 in kick strength with nominal LHC beam (to be checked with totem beam)
(decoherence in 2ms, ms calculated by Roberto)
Chromaticity could be lowered by a factor 2 in 2007 (new PFW power supplies)
What ‘s unknown (yet)?
Impedance transformer characteristics
A.B February 2005
AB-RF-FB section meeting

8. AB-RF-FB section meeting
PS TFB
Amplifiers
Initial requirements
Bandwidth: [10kHz - 20 MHz]
3 kW on 12.5 Ω
Actual performances
Bandwidth: [100kHz - 35MHz]
3 kW – 2 ms, 100 W CW
What ‘s unknown?
Precise phase response
A.B February 2005
AB-RF-FB section meeting

9. AB-RF-FB section meeting
PS TFB
Amplifiers
What’s wrong?
The first Betatron line (q. FREV) is not covered
Does it matter?
There are two answers to this question, one valid for injection damping, the other for h-t instabilities
( Injection damping is faster than the growth rate of h-t instabilities -1ms vs 10 to 100 ms)
During injection, what matters is the spectrum of the beam. Less than 8 % of the energy is in the first Betatron line. If it isn’t driven instable, there should be only 8% less damping efficiency in linear regime and almost no difference in saturation mode.
For h-t modes, only the negative (n+Q).FREV lines are instable, but somehow “compensated” by the positive spectral lines… except (when ξ≠0) for the first negative line n = -7 or (1-q).FREV .
As q Є [ ], n = -7 mode Є [348 kHz, 261 kHz]. This instable line is covered by the amplifier. Of course the q.FREV line should be “electronically” stable.
Is there a proof?
see next slide !
A.B February 2005
AB-RF-FB section meeting

10. AB-RF-FB section meeting
PS TFB
Amplifiers
Is there a proof that the system would work with 100 kHz HP cutoff?
Injection error damping with wideband feedback
Simulations from Elmar turns/div
With H.P.
A.B February 2005
AB-RF-FB section meeting

11. AB-RF-FB section meeting
PS TFB
Amplifiers
details of the simulation
Is there a proof concerning h-t instabilities?
It is a well established theory !
A.B February 2005
AB-RF-FB section meeting

12. AB-RF-FB section meeting
PS TFB
Amplifiers
Has everything been taken into account?
e-p instabilities: not observed in the PS !
h-t modes: have a damping effect with positive ηξ (both negative at PS injection) => positive chromatic frequency. It damps the injection errors with a time constant of 5 ms (20 ms total damping) without emittance blow-up (simulation by Elias)
Chromaticity and Chromatic frequency: it changes the instable m-mode but not the
frequency at which it should be corrected. In 2007 we might have a lower ξ => less kick requirements
Broadband impedance: should damp the lower modes without blow-up.
Under simulation (E. B. + F. Z.)
Space charge: it is beneficial as it increases the filamentation time.
Octupolar tune: speeds-up filamentation but not foreseen in normal operation
Real kicker ripple (30 MHz): ok with the amplifier (35 MHz)
A.B February 2005
AB-RF-FB section meeting

13. AB-RF-FB section meeting
PS TFB
Electronic core
How do we do?
Use of LHC 1TFB and TFB hardware made compatible with minor add-ons
Specific FPGA programming software
A.B February 2005
AB-RF-FB section meeting

14. AB-RF-FB section meeting
PS TFB
Budget
No budget allocation for kCHF need to be found!!
- 3kW power loads: 10k
- Impedance matching transformers: 8k (6k FSU + 2k material)
- Kicker modification (mechanical setup for fixing Xformers and loads + install new feedthroughs):
8k (7k FSU + 1k material)
- Interlock circuit design and construction: 16k (6k study + 10k construction)
- Construction of circuits developed for LHC: 12k
- VME crate to plug new PCBs : 10k
- Strip-line Kicker modification: 15k (5k mech. Study, 10k construction and material)
- Power amplifiers modification: 35k (in case we do not change the PCB's)
- Cabling in racks: 4k
- Ceramic pipes end work: 10k
- Unexpected: 5k
Total: 133 kCHF
What has been spent:
H/V kicker study: 100k
H kick construction: 100k
Ceramic pipes: 100k
Electronics, cabling: 50k
Total: 350k
Originally planned: 360k
A.B February 2005
AB-RF-FB section meeting

15. AB-RF-FB section meeting
PS TFB
Workload
- 3kW power loads: 1 W
- Impedance matching transformers: 4 W
Kicker modification : 4 W
Interlock circuit design and construction: 7 W
- Construction and test of circuits developed for LHC: 3 W
- VME crate: 1 W
- Strip-line Kicker modification: 4 W
- Power amplifiers modification: 12 W
- Cabling in racks: 1 W
Ceramic pipes end work: 1 W
FPGA programming: 8 W
Supervision: 3 W
Unexpected: 3 W
Commissioning (hard + beam): W
Total: 58 W
A.B February 2005
AB-RF-FB section meeting