RF 1/33 ALBA RF system why, how and other questions Francis Perez

RF 2/33 Contents WHY? HOW? WHICH? Other questions

RF 3/33 WHY? we need a RF System to: –accelerate the electron beam to high speeds (~c) / high energy –restore the energy loss via synchrotron radiation of the stored e - beam –provide a stable energy bucket to ensure a long lifetime

RF 4/33 WHY? To accelerate the electron beam to high speeds (~c) / high energy –1st in the LINAC: 90 keV to 100 MeV –2nd in the BOOSTER: 100 MeV to 3 GeV

RF 5/33 WHY? To restore the energy loss via synchrotron radiation of the stored e - beam V = E eff. gap 400 mA 1.3 MeV/turn 520 KW Energy Time T revolution 881 ns Cavity Voltage 3.0 GeV 1.3 MeV 1.3 MV

RF 6/33 WHY? provide a large stable energy bucket to ensure a long lifetime of the stored e - beam High Voltage Low Voltage For ALBA SR:3.6 MV 3% Energy Aceptance

RF 7/33 HOW? inside the RF cavities an electromagnetic field is stored –and we will make use of: –to create a force that will accelerate the electrons create a stable well potential F = q E

RF 8/33 HOW? The electrons are moving and the e-m field oscillating F = q E E(s,t) = E 1 (s).E 2 (t) at the cavities elsewhere Electrons are bunched: ~10 mm long 600 mm apart

RF 9/33 HOW? in the LINACto 100 MeV 70 MW pulsed 3.5  s Which provides effective ~100 MV of accelerating voltage for the e - beam in ~10 meters

RF 10/33 HOW? in the BOOSTERto 3 GeV 1 cavity (5 cells) 60 kW cw to produce 1.2 MV the e- beam will be accelerated in ~150 ms, 3 times per second

RF 11/33 HOW? in the SRat 3 GeV N cavities to provide 520 kW for the beam to provide 3.6 MV 3% energy acceptance

RF 12/33 WHICH Cavity? NC 100 MHz MAXlab NC 180 MHz BNIP SC 352 MHz SOLEIL NC 500 MHz ELETTRA NC 500 MHz EU SC 500 MHz CORNELL

RF 13/33 ELETTRA Total Voltage3.6MV No Cells/IPC6 Type of cavitync Voltage / cell600kV R shunt 3.4MW Cavity power53kW Beam power/cav87kW IPC power140kW Amplifier Power160kW Total Power960kW

RF 14/33 EU project Total Voltage3.6MV No Cells/IPC6 Type of cavitync Voltage / cell600kV R shunt 3.0MW Cavity power60kW Beam power/cav87kW IPC power147kW Amplifier Power160kW Total Power960kW

RF 15/33 SC CORNELL Total Voltage3.6MV No Cells/IPC2 Type of cavitysc Voltage / cell1800kV R shunt 4500MW Cavity power0kW Beam power/cav260kW IPC power260kW Amplifier Power300kW Total Power600kW

RF 16/33 Which cavity? (1) ELETTRA(2) EU(3) CORNELL DC POWER2.5 MW2.6 MW2.1 MW WATER COOLING 220 m 3 /h230 m 3 /h140 m 3 /h Cavity Wall Dissipation Refrigerator Turbines

RF 17/33 (1) ELETTRA(2) EU(3) CORNELL SPACE2 x 2.9 m 2 x 3.3 m 3 cavities in one 4 m straight 1 cavity in one 4 m straight COST ESTIMATION 9.3 M€9.9 M€ +600 k€ 10.6 M€ k€ 6 x 1.55 M€6 x 1.65 M€2 x 5.3 M€ Which cavity?

RF 18/33 COST DIFFERENCES (1) ELETTRA (2) EU(3) CORNELL INVESTMENT0+600 k€+1300 k€ RUNNING (10y) (6000 h/year, 0.1 €/kWh) k€+3000 k€0 MAN POWER (10y) (1.5 man/year) k€ TOTAL+2400 k€+3600 k€+2200 k€ COST DIFFERENCE OVER 10 YEARS +200 k€+1400 k€0 SPACE, SERVICES and COST are NOT DECISION FACTORS Which cavity?

RF 19/33 HOM instabilities A RF cavity has more than just the fundamental resonance frequency at 500 MHz HOMs Other questions

RF 20/33 HOM instabilities When a multiple of the revolution frequency „hits“ a HOM a resonance condition arise and a instability is created. f HOM = n f rev (plus sidebands) StableInstable

RF 21/33 Comparison: Longitudinal HOMs Stability threshold for 400 mA Cavity temperature tuning should reduce the ELETTRA HOMs impedances

RF 22/33 Comparison: Transverse HOMs Stability threshold for 400 mA Stability because the cavities are in a low beta section (2 m)

RF 23/33 WHICH CAVITY? SC assures beam stability, but recovery time after failure is longer… NC has shorter recovery time after failure, but needs extra care to assure beam stability Beam stability vs. Beam availability

RF 24/33 Cavities Klystron Cooling Rack HVPS NC RF

RF 25/33 Cavity Gas reservoir Dewar Turbines Valve Box SC RF

RF 26/33 Total Voltage3,6MV Number Cells6 Voltage per cav600kV Shunt Impedance3,4Mohm Cavity power53kW Beam power / cell87kW IPC power140kW Amplifier Power160kW Number Amplifiers6 RF Amplifier Other questions NC

RF 27/ kW amplifier (IOTs) CAVITY HVPS + Amplifier 160 kW CAVITY … x 6 HVPS + Amplifier 160 kW Other questions RF Amplifier NC

RF 28/33 Total Voltage3,6MV Number Cells2 Voltage per cav1800kV Shunt Impedance4500Mohm Cavity power0,4kW Beam power / cell260kW IPC power260kW Amplifier Power>280kW Number Amplifiers2 SC Other questions RF Amplifier

RF 29/ kW amplifier (klystron/IOT) CAVITY HVPS +Amplifier 300 kW CAVITY HVPS + Amplifier 300 kW SC Other questions RF Amplifier x 2

RF 30/ kW Amplifier: Klystron vs IOTs combination

RF 31/ kW Amplifier IOT combination via a cavity combiner: 80 HVPS CAVITY 300 kW

RF 32/33 Cavity combiner We want to produce a power prototype E. Wooldridge, ASTeC

RF 33/33 SUMARY RF is needed at: –LINAC turn key system –BOOSTER 5 cell cavity, 60 kW –Storage Ring NC vs SC under discussion Klystron vs IOTs Cavity combiner prototype