C/S band RF deflector for post interaction longitudinal phase space optimization (D. Alesini)

Slice parameter measurements by RFD: principle K cal resolution RFD OFFRFD ON High res. Low res. The different types of measurements that can be done with RFDs are based on the property of the transverse voltage (V DEFL ) to introduce a linear correlation between the longitudinal coordinate of the bunch (t B ) and the transverse one (vertical, in general) at the screen position (y S ).

Slice parameter measurements by RFD: principle RFD OFF RFD ON Typical SPARC parameters Self calibrated meas. The coefficient K cal can be directly calculated measuring the bunch centroid position on the screen for different values of the RFD phase resolution

 N =1 [mm*mrad] f RF =2.856 [GHz]  S =1 m   yB  18  m GeV)   yB  58  m MeV) L Defl-Screen =4 m RF Deflecting structures: SW vs TW performances TW SW or TW SWTW Efficiency per unit lengthHighLow Filling timeslowfast Maximum number of cells1580 CirculatoryesNot Beam impactlowHigh Because of the higher surface electric field, SW multi-cell devices can be used with input power below MW giving V DEFL <10 MV

E, B field profiles RF Deflecting structures: SW case (SPARC RFD) RFD in the LNF oven RFD installed in SPARC Input coupler Active cells SW structures are multi cell devices working, for example, on the  - mode. Theses structures have, in general a higher efficiency per unit length with respect to the TW ones but the maximum number of cells is limited to few tens because of mode overlapping. They requires circulators to protect the RF source from reflections.

P RF Beam deflection f RF =2.856 GHz MODE 2  /3 H Field E Field 2a Backward (H coupling) Forward (E coupling) RF SEPARATORS RFD DIAGNOSTICS CTF3 RFD TM 11 -like RF Deflecting structures: TW case y Direction of deflection Transverse position along the iris [mm] x As in the case of accelerating sections, we have TW and SW cavities. In general RFDs are multi-cell devices working on the TM 11 -like mode. Both the E and the B field contribute to the total deflection. The transverse force is uniform over a wide region inside the iris aperture In TW devices the iris aperture (a) is the most important parameter to fix the deflection efficiency and group velocity

GUN Klystron N°1 ≈ 13 MV/m ACC. SECTION 20 ÷ 22 MV/m ≈ 130 MeV ACC. SECTION PULSE COMPRESSOR ATT 3 dB splitter C-band Station C-band ENERGY COMPRESSOR C-band acc. structures > 35 MV/m 5712 MHz – 50 MW 1.4 m ≈ 90 MW ≈ 180 MW/0.20 μs 2.5 μs Klystron N°2 C/S band RF deflector for post interaction: POWER SOURCES (1/2) Present situation of power distribution

GUN Klystron N°1 ACC. SECTION 20 ÷ 22 MV/m ≈ 130 MeV ACC. SECTION PULSE COMPRESSOR ATT 3 dB splitter C-band Station C-band ENERGY COMPRESSOR 5712 MHz – 50 MW 1.4 m ≈ 90 MW ≈ 180 MW/0.20 μs 2.5 μs Klystron N°2 1  s, f RF =2.856 GHz P in max =15 MW 0.2  s, f RF =5.712 GHz P in max =15 MW After the C-Band energy upgrade C/S band RF deflector for post interaction: POWER SOURCES (2/2)

S-BAND RF DEFLECTOR SW OPTION 1  s, f RF =2.856 GHz P in max =15 MW PS ATT PARAMETERS f [GHz]2656 Number of cells11 Length [m]0.60 Q0Q R T [MΩ]5.5 Input coupling  2.5 Filling time  [ns] 477 Pulse duration T pulse [ns]1100 RF input power [MW]13 Deflecting voltage [MV]9.7 Resolution [fs]29 SWITCH COST [k€] deflector40 Waveguides (~15 m)20 Phase shifter15 Attenuator20 Circulator25 Switch/attenuator25 TOTAL145

C-BAND RF DEFLECTOR SW OPTION PS ATT PARAMETERS f [GHz]5712 Number of cells11 Length [m]0.30 Q0Q R T [MΩ]3.85 Input coupling  3 Filling time  [ns] 150 Pulse duration T pulse [ns]200 RF input power [MW]13 Deflecting voltage [MV]6.5 Resolution [fs]21 SWITCH COST [k€] deflector40 Waveguides (~15 m)20 Phase shifter15 Attenuator20 Circulator25(?) Switch/attenuator20 TOTAL140 (?) 0.2  s, f RF =5.712 GHz P in max =15 MW IF CIRCULATOR AVAILABLE

C-BAND RF DEFLECTOR TW OPTION PS PARAMETERS f [GHz]5712 Number of cells29 Length (with couplers) [m]0.6 Z T [MΩ/m 2 ]12.7 Filling time  [ns] 50 Pulse duration T pulse [ns]200 RF input power [MW]13 Deflecting voltage [MV]6 Resolution [fs]23 COST [k€] deflector40 Waveguides (~15 m)20 Phase shifter15 Attenuator20 Switch/attenuator20 TOTAL  s, f RF =5.712 GHz P in max =15 MW ATT SWITCH

S-BAND VS C-BAND PRO S-BAND SW -standard technology, easy procurement, probably lower cost BUT -nothing new… PRO C-BAND TW -exploring the new technology -synergies with PSI ($?) BUT -spill-out power from acceleration (about 15 MW) -probably critical procurement of standard components C-BAND SW…. similar to TW BUT require Circulator (?)…. NB. Circulator is necessary for C-BAND gun unless to consider other compensation schemes…