M. Paoluzzi BE/RF 1

A longitudinal damper for the PS(preliminary ideas)

24 April 2012

M. Paoluzzi BE/RF 224 April 2012

Specifications

Just some basic specifications are now available for the PS longitudinal wide-band kicker.

• The lowest mode to be damped is at the revolution frequency : ~400 kHz • The highest is half the bunch frequency : ~5 MHz• The RF voltage required is of the order of : ~5 kV.

• As the feedback will damp several modes simultaneously, RF voltage will be generated at several frev harmonics (i.e. synchrotron frequency side-bands) simultaneously.

• The kicker impedance should be comparable with that of a C10 cavity (~150 Ω)• To not jeopardize beam stability in case of problems, the cavity must be

equipped with gap short-circuits.

M. Paoluzzi BE/RF 324 April 2012

Use broadband LEIR cavity

• Performances almost compatible.• Low frequency voltage increasable limiting the duty-cycle (i.e. 4kV at 50% )• Gap voltage increasable with adding additional cores (8 instead of 6).• One power amplifier already available!

Frequency MHz 0.35 0.7 2 5.0Nominal gap voltage kV 2 4 4 4

Cavity power kW 5 18 14 12

Cavity Rgap W 390 450 570 660

Cavity |Zgap| W 275 390 560 320

Max power density W/cm3 0.2 0.8 0.7 0.6

Average power density W/cm3 0.1 0.4 0.3 0.3

424 April 2012 M. Paoluzzi BE/RF

Voltage improvement with low loss Finemet® (FT3L).

With the new low-loss Finemet® type FT3L higher voltages can be achieved.

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

2

4

6

8

10

12

14

FT3M and FT3L Finemet® µQf characteristics

uQf(FT3L,13um)

uQf(FT3M,18um)

frequency （ MH ｚ）

uQ

f (G

Hz)

Core losses (RP) are proportional to µQf. Almost a factor 2 improve achievable with FT3L!

Kin

dly

pro

vid

ed

by D

r. C

hih

iro O

hm

ori

(K

EK

)

524 April 2012 M. Paoluzzi BE/RF

Wideband system capacitance compensation.

•With the low-loss Finemet® RP increases but the system capacitance stays constant.

•To make full use of the Finemet® wideband properties it is essential to use different capacitance compensation approach.

10

1000

0.1 1 10 100MHz

Oh

m

C=24pF

Cavity aloneNo accessories

No cooling water.

C=95pF

Full systemWith cooling water.

RF Choke series resonance.

High wideband impedance seen by the beam!!!Need some kind of cancellations scheme.

M. Paoluzzi BE/RF 624 April 2012

Use broadband PSB cavity

• Frequency coverage compatible with requests.

• Modular system providing ~700V per cell.• Voltage limited by the power amplifier• Easily increasable to 1kV.

• Existing design for 5 cells system.

… but:

• Are solid-state components admissible in the PS machine?

• Can the required power be provided by solid-state amplifiers.

B E A M

F I N E M E T

G A P

R F i n

G a p

M. Paoluzzi BE/RF 724 April 2012

Planning.

Spring-Summer 2012 : Preliminary study • Identify location• Select technology• Evaluate radiation damage risks

Autumn-Winter 2012 : System design• Cavity electrical design (Collaboration established with KEK and J-PARC)• Power sections and ancillary electronics design

Spring-Summer 2013 : Procurements and manufacturing

Autumn-Winter 201 : Assembly and tests

Beginning 2014 : Installation