100 likes | 231 Views
BASIC CONSIDERATIONS Present performance : 1E13p from 50 MeV to 1.4 GeV in 490 ms (1.2s cycle) New Goal : 2E13p from 160 MeV to 2 GeV in 325 ms (0.6s cycle). 0.9s and 0.6s cycle data obtained from Alan and José (actual MD values)
E N D
BASIC CONSIDERATIONS • Present performance: 1E13p from 50 MeV to 1.4 GeV in 490 ms (1.2s cycle) • New Goal: 2E13p from 160 MeV to 2 GeV in 325 ms (0.6s cycle). 0.9s and 0.6s cycle data obtained from Alan and José (actual MD values) • 36% more energy increase in 66% of the initial time, means roughly an average* rf power multiplied by two (1.36/0.66) together with a 3% frequency increase. • *Average means average during the acceleration itself; an increase of a super-cycle duty cycle needs to be taken into account for the power cooling system PSB rfForeseen limitations with 2 E13 p at 2 GeV PSB RF 2GeV 10/03/2010
Implications for the PSB low-level rf: • 1.4 GeV : FREV = 1.75 MHz, FS = 446 Hz (h1,8kV) • 2 GeV : FREV = 1.81 MHz, FS = 256 Hz (h1,8kV) • The increase of FREV has no impact on the beam control • The increase of B (8671 -> 11273 Gauss) requires having a B train counter well dimensioned (>17 bits). • The 0.6 s cycle is very likely to require a zero flat-top duration and thus a zero duration synchro(no theoretical problem but may be processing power limitations!?) • The change of FS (1680 Hz at 160 MeV, 256 Hz at 2 GeV (h1/8kV)) might require loop parameters to be programmed as functions (not constant)… may be this already the case !? (to be checked with Maria-Elena) • Short cycles might reduce the time reserved to download the rf parameters into the beam control system and calculate the GFA functions (to be checked with Maria-Elena and Andy) PSB rfForeseen limitations with 2 E13 p at 2 GeV PSB RF 2GeV 10/03/2010
Implications for the PSB transverse feedback: Beam current multiplied by 2.07 => required power multiplied by 4.3 The increased beam rigidity (+ 30% from 1.4 to 2 GeV) doesn’t play a role except for blow-up purposes… nevertheless a multiplication by 8 of the power is foreseen! PSB rfForeseen limitations with 2 E13 p at 2 GeV PSB RF 2GeV 10/03/2010
Compromise at low energy: • High intensity • high space charge • must increase emittance (painting) • must keep high acceptance => φS small (for same rf voltage) • must prolong acceleration => good for dipole power supplies + good for rf power. • To have a faster cycle => increase rf voltage… and the rf power by the same amount PSB rfForeseen limitations with 2 E13 p at 2 GeV PSB RF 2GeV 10/03/2010
Summary: • RF power is a function of the acceleration time: the longer the acceleration the lower the power • RF power is a function of the beam current: the higher the current, the higher the required power. • RF voltage is a function of the acceleration duration: the faster the acceleration, the higher the voltage for the same acceptance. • We can either specify tough constraints for the rf power taking into account the most ambitious beam, or set lower constraints and foresee cycles lengths as a function of the intensity. PSB rfForeseen limitations with 2 E13 p at 2 GeV PSB RF 2GeV 10/03/2010
What can be supplied to the task force: • rf power specifications for the possible most demanding beam (2E13p, 2 GeV, 0.6 s) • Lessen rf power specifications with cycle lengths as a function of the intensity (1.2 s for 2E13p, 2 GeV),(0.6 s for <1E13p, 2 GeV)… • More specifically from Mauro: how could this be made • Information needed: • Max Bdot of the new power supply (likely to be > 35.7 G/ms = 27.5 (present max) * 11273/8671 PSB rfForeseen limitations with 2 E13 p at 2 GeV PSB RF 2GeV 10/03/2010
New Requirements: 2E13 p per ring (maximum intensity injected from Linac 4) instead of 1E13p as presently. 2GeV maximum kinetic energy at extraction (1 and 1.4 GeV also available) Cycle durations: 1.2 , 0.9 and 0.6 s 1.2s => inj=C275, flat-top=C765, ej=C805 => acceleration=490ms, flat-top=40ms 0.9s => inj=C175, flat-top=C575, ej=C615 => acceleration=400ms, flat-top=40ms (info A. Findlay) 0.6s => inj=C46, flat-top=C389=ej => acceleration=343ms, flat-top=0ms (info J.L. Sanchez) PSB rfForeseen limitations with 2 E13 p at 2 GeV PSB RF 2GeV 10/03/2010
PSB rfForeseen limitations with 2 E13 p at 2 GeV PSB RF 2GeV 10/03/2010
PSB rfForeseen limitations with 2 E13 p at 2 GeV Dipolar field; Present power supply limitations: 1.2 T/s -> 2.7 T/s (max value) => 65 ms 2.7 T/s -> 0 T/s => 135 ms PSB RF 2GeV 10/03/2010
Beam loading in cavities PSB RF 2GeV 10/03/2010