1 MW AGS proton driver M J Brennan
1 MW AGS proton driver (M. J. Brennan, I. Marneris, T. Roser, A. G. Ruggiero, D. Trbojevic, N. Tsoupas, S. Y. Zhang) Parameters and layout Beam loss considerations 1. 2 Ge. V Superconducting Linac 2. 5 Hz AGS power supply and rf system 4 MW Upgrade Bunch compressor ring Cost estimate Thomas Roser Snowmass 2001 June 30 - July 21, 2001
AGS proton driver parameters 1 MW AGS presently Total beam power [MW] 1 0. 14 Beam energy [Ge. V] 24 24 Average current [m. A] 42 6 Cycle time [ms] 400 2000 No. of protons per fill 1 1014 (0. 6 - 0. 7) 1014 Average circulating current [A] 5. 9 4. 2 No. of bunches per fill 6 6 No. of protons per bunch 1. 7 1013 ~ 1 1013 Time between extracted bunches [ms] 20 33 Rms bunch length [ns] 3 30 Peak bunch current [A] 400 30 Total bunch area [e. Vs] 5 15 Rms bunch emittance [e. Vs] 0. 3 0. 8 Rms momentum spread 0. 005 0. 001
AGS proton driver layout To RHIC High Intensity Source plus RFQ To Target Station 116 Me. V Drift Tube Linac (first sections of 200 Me. V Linac) BOOSTER AGS 1. 2 Ge. V 24 Ge. V 0. 4 s cycle time (2. 5 Hz) 400 Me. V Superconducting Linacs 800 Me. V 1. 2 Ge. V 0. 15 s
Beam loss at H injection energy AGS Booster PSR Beam power, Linac exit, k. W Kinetic Energy, Me. V 200 Number of Protons NP, 1012 Vertical Acceptance A, p mm b 2 g 3 0. 57 4. 50 6. 75 NP / (b 2 g 3 A), 1012 / p mm 0. 296 Total Beam Losses, % 5 Total Loss Power, W 150 Circumference, m 202 Loss Power per Meter, W/m SNS 3 800 15 89 9. 56 0. 049 0. 3 240 90 0. 8 1 MW AGS 80 1000 1200 31 100 140 480 0. 031 0. 1 1000 248 2. 7 0. 190 3 1440 807 4. 0 50 100 55 1. 8
Beam losses in AGS Major loss points Present AGS % particles. Beam power Injection and early accel. : Controlled Uncontrolled 30 % 1. 9 k. W 1 MW AGS % particles. Beam power Transition 2. 0 % 0. 4 k. W 2. 9 k. W Total: 2. 3 k. W l l l 1. 0 % 3. 0 % 0. 3 % 1. 5 k. W 0. 2 k. W 4. 6 k. W Injection modeled after SNS but much lower repetition rate and less foil traversals Allow 30 times more beam loss Transition losses are presently dominated by beam momentum spread required for AGS injection stacking. Direct injection should eliminate chromatic transition losses. 4. 6 k. W should be acceptable for hand maintenance.
AGS injection simulation Injection parameters: Injection turns 360 Repetition rate 2. 5 Hz Pulse length 1. 08 ms Chopping rate 0. 65 Linac average/peak current 20 / 30 m. A Momentum spread 0. 15 % Inj. beam emittance (95 %) 12 p mm RF voltage 450 k. V Bunch length 85 ns Longitudinal emittance 1. 2 e. Vs Momentum spread 0. 48 % Circ. beam emittance (95 %) 100 p mm
1. 2 Ge. V Superconducting Linac Beam energy 0. 116 0. 4 Ge. V 0. 4 0. 8 Ge. V 0. 8 1. 2 Ge. V Rf frequency 805 MHz 1610 MHz Accelerating gradient 11. 9 Me. V/m 22. 0 Me. V/m 21. 5 Me. V/m Length 75. 4 m 43. 9 m 42. 6 m Beam power, linac exit 17 k. W 34 k. W 50 k. W
New AGS main magnet power supply l l l presently: Repetition rate 2. 5 Hz 1 Hz Peak power 110 MW 50 MW Average power 4 MW Peak current 4. 2 k. A 5 k. A Peak total voltage 25 k. V 10 k. V Number of power converters / feeds 6 2
Distribution of current feeds
AGS rf system upgrade Use present cavities with upgraded power supplies (two 300 k. W tetrodes/cavity) Rf voltage/turn harmonic number Rf frequency Rf peak power Rf magnetic field 1 MV 24 ~ 9 MHz 3 MW 18 m. T presently: 0. 4 MV 6 - 12 3 - 4. 5 MHz
Bunch merging and compression Adiabatic quad pumping: h = 24 1. 2 e. Vs/bunch Adiabatic merging: h=6 100 k. V/turn ~ 5 e. Vs/bunch h = 24 1 MV/turn 80 ns 15 ns (3 ns rms)
Phased AGS intensity upgrade present AGS 0. 4 MW AGS 1 MW AGS SC Linac No Yes AGS PS upgrade No No Yes Total beam power [MW] 0. 14 0. 4 1. 00 Beam energy [Ge. V] 24 24 24 Average current [m. A] 6 17 42 Cycle time [ms] 2000 1000 400 No. of protons per fill 0. 7 1014 1 1014 Average circulating current [A] 4. 2 5. 9 No. of bunches at extraction 6 6 6 No. of protons per bunch ~ 1 1013 1. 7 1013 Total bunch area [e. Vs] 15 Time betw. extr. bunches [ms] 5 33 5 20 20
Towards 4 MW Upgrade I Linac intensity/pulse Linac rep. rate 2. 5 Hz Linac extraction energy b 2 g 3 9. 6 14. 9 Beam power 54 k. W AGS intensity/pulse AGS rep. rate 2. 5 Hz Rf peak power 3 MW Rf gap volts/turn 1 MV AGS extraction energy Beam power 1 MW Bunch area 5 e. Vs Compressor ring no Upgrade III 1. 2 1014 2. 4 1014 2. 5 Hz 5. 0 Hz 1. 2 Ge. V 1. 5 Ge. V 14. 9 144 k. W 288 k. W 1. 0 1014 2. 5 Hz 5. 0 Hz* 6 MW 8 MW 1 MV 1. 5 MV 24 Ge. V 2 MW 4 MW 10 e. Vs yes * Symmetric cycle (0. 1 s up, 0. 1 s down) without flattop. 2. 4 1014 2. 0 1014
4 MW AGS proton driver layout To Target Station 24 Ge. V Superconducting Compressor Ring To RHIC High Intensity Source plus RFQ 24 Ge. V Superconducting Storage Ring 116 Me. V Drift Tube Linac (first sections of 200 Me. V Linac) BOOSTER AGS 1. 2 Ge. V 24 Ge. V 0. 2 s cycle time (5 Hz) 400 Me. V Superconducting Linacs 800 Me. V 1. 5 Ge. V 0. 1 s
Compressor ring Small superconducting ring to compress a single 24 Ge. V, 10 e. Vs bunch to 3 ns rms length. Small size reduces space charge tune shift and gap volt requirements. l Circumference 200 m l Energy 24 Ge. V l Dipole field ~ 4 Tesla l Packing factor 60 % l Transition gamma ~ 40 (dg. T/dg < 4) l Momentum acceptance 5 % (FFAG type lattice? ) l Rf frequency 6 MHz (h = 4) l Rf Voltage per turn 200 k. V l Bunch length compression (rms) 20 ns 3 ns
Bunch compression
- Slides: 16