Title: A 10 GeV, 4 MW, FFAG, Proton Driver at 50 Hz
1A 10 GeV, 4 MW, FFAG,Proton Driver at 50 Hz
2Non-scaling, Non-linear FFAGs
- Categories for FFAG Lattice Cells of Five
Magnets - 1. IFFAG isochronous, no Qvn and 2Qvn crossing
- 2. IFFAGI IFFAG with combined function
insertions - 3. NFFAG non-isochronous, high/imag ?-t, no Q
varn - 4. NFFAGI NFFAG with insertions, some Qh
variation - 1 and 2 rapid acceleration of muons or
electrons - 3 and 4 high power proton drivers or medical
rings
34 MW Proton Driver Arrangement
- Muon yields optimal for 6 - 10 GeV (S Brooks,
RAL) - Choose 10 GeV, 50 Hz to reduce target shock
- 3 GeV booster for 3 10 GeV
NFFAGI - 2, 25 Hz or 1, 25 Hz booster (R
2.2 Rb) - 0.18 GeV H? linac for low bunch
areas - 5 bunches at h 5 for RCS
booster(s) - Transfer 5 (1013 protons/bunch) to the NFFAGI
- Bunch to 1 ns (rms) adiabatically (h 33 198)
4Longitudinal bunch area
- The longitudinal bunch area (in eV sec) is
- A (8Ra/(ch)) ((2 V(I-?sc)Eo?) / (h??))½
-
- For a small longitudinal bunch area, choose
- a low value of injection energy and ring radius
- Choose Eo (? - 1) 0.18 GeV and Rb ? 50.0 m
- Choose the bunch harmonic number (h) 5
- Compressed bunch area needed ? 0.66 eV sec
54 MW, Proton Driver Layout
0.18 GeV H ? Linac
0.18 GeV H ? Achromat
3 GeV, 50 Hz, h 5, RCS (1 at 50 Hz, or 2 at 25
Hz)
10 GeV, 50 Hz, N 5, NFFAGI with 1013 protons
per bunch
6NFFAGI Design Criteria
- For compression of the 5 bunches at 10 GeV
- Design for a gamma-t value at 10 GeV ? 20
- Design for longitudinal bunch areas ? 0.66 eV s
- Adiabatic acceleration comp. with h 33, 198
- Design the NFFAG ring with lattice insertions, to
- ease injection, ejection beam loss collection
- Use two insertions to allow most flexibility, eg
- 21 normal and 13 insertion cells per insertion
7Acceleration and Compression Systems
- Driver-booster circumference ratio 2.2 to 1
- Booster rf range (h5) 2.6164 to 4.670 MHz
- Driver rf range (h33) 14.011 to 14.370 MHz
- Compression frequency (h198) 86.222 MHz
- Peak accelerating voltage per turn 1.0 MV
- Peak compression voltage per turn 2.56 MV
8Lattice Cell Options
- Normal cell Insertion cell
Magnet types - Doublet D D1 T0 D2
2 7 - Triplet T T1 T2 T1
2 4 - Pumplet P1 P2
3 3 - Easiest solution is to match P1 and P2 pumplet
cells -
- P1 has a smaller ß-range than either D or T
- The insertion has only one type of cell, P2
- P2 has the smallest closed orbit lever arm
- No 2? dispersion suppressors, as too many are
needed
910 GeV, Normal Insertion Cell Layouts
- bd(-) BF() BD ()
BF() bd(-) - O 0.5 0.5
0.5 0.5 O
- 0.60 1.25 1.9
1.25 0.60 - 0.651 Normal cell (5.294º, 8.902
m) 0.651 - 2.2 Insertion cell (5.294º,
12.00 m) 2.2 -
- There are two superperiods of 21 normal 13
insertion cells -
- At 10 GeV Qv 13.72, Qh 19.36, ? -t
20.4, R 109.17 m -
10NFFAGI Lattice Design
- Use equal bend, normal and insertion, pumplet
cells - Arrange matching for a normal and insertion
cell - Arrange integer, insertion tunes eg Qh 4 Qv
3 - The normal cells in an insertion are then matched
- Seek unchanged closed orbits on adding insertions
- by varying the normal cell field gradients and
tunes - Then, dispersion match is almost exact for
insertions - Small ripple remains in ßh and ßv (max) in
insertions
11Non-Linearity Compensation
- Crossing of the 3rd order resonance 3Qh
58 - Insertion and arc 3(Qh ) values 3Qh
3(4, 5? ) - Hence, no 3rd order excitation for 3Qh
58 - Crossing of 4th order resonance 2Qh 2Qv 66
- Insertion and arc values for 2(Qh Qv )
2(7, 9½ ) - So, no 4th order excitation for 2Qh 2Qv 66
- Crossing of the 4th order resonance 4Qh
77 - Insertion and arc 4(Qh ) values 4Qh
4(4, 5? ) - Some small 4th order excitation for 4Qh 77
12NFFAGI Lattice Results
- Satisfactory matching at the 24 reference
energies - 10.0..6.8, 6.5..5.0, 4.75..4.0, 3.8..3.0 GeV.
- Qv 13.72 throughout the 3 to 10 GeV energy
range. - Dispersion match is found by varying K(bd) and
?h - T 10.06.8, 6.5. 5.0, 4.75..4.0, 3.83.0
GeV - Qh19.36, 19.31, 19.3, 19.29, 19.2, 19.2, 19.2,
19.2 - Gamma-t becomes imaginary for the low energies
13Combined Function Magnet Fields (T)
- Magnets Insertion
Normal cell - bd -1.70 to -1.18
-1.70 to -0.98 - BF 1.75 to -0.15
1.75 to -0.27 - BD 0.54 to 1.55
0.54 to 1.59 - Tmax bending ratios bd BF BD - 0.47 1.0
0.23 - (Ratios in muon ring bd BF BD - 1.0
1.0 1.0)
14Beam Loss Collimators
- Vertical
- Locate in 4, adjacent, long, insertion straights
- Use 1, primary and 3, secondary, 5 kW collimators
- Use tapered units for lower, high energy
acceptance - Horizontal
- Locate in the first three, vertical, collimator
straights - Use 1, primary and 3, secondary, 5 kW collimators
- Use angled units for collimation at 3 and 10 GeV
1510 GeV NFFAGI versus RCS
- Pros Allows acceleration over more of the cycle,
- No need for ac magnet p/s or ceramic chamber,
- Gives more flexibility for the holding of
bunches, - Required is one NFFAGI ring, but two RCS(s),
- Allows operation at 50 Hz instead of at 25 Hz,
- with 5 1013 ppp at target, instead of 1014 ppp.
- Thus, there is half the target shock per pulse.
- Cons needs a larger ( 0.33 m) radial aperture