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CEA PROPOSITION FOR SARAF-PHASE 2 LINAC – DESIGN ET BEAM DYNAMICS
MARCH 20TH, 2014
EuCARD-MAX workshop at CERN
| PAGE 1
SARAF BEAM TOP LEVEL REQUIREMENTS (TLR)
Particles : deuterons and protons
Input energy : 20 keV/u
Input emittance (rms, norm.) : 0.2 p.mm.mrad
Output energy : 1.3 MeV/u 40 MeV
Emittance growth < 25%
Time structure : 0.1-1 ms @ 0.1-400 Hz cw
Beam current : 0.04 – 5 mA
Beam losses :< 150 nA/m for E < 5 MeV (0.4-0.75 W/m)< 40 nA/m 10 MeV (0.2-0.4 W/m)< 5 nA/m 20 MeV (0.05-0.1 W/m)< 1 nA/m > 20 MeV (0.02-0.04 W/m)
<< 1 W/m !!!
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 2
CEA PROPOSITION @ 176MHZ
RFQ MEBT CM1 CM2 CM2 CM3
3.85 m 2.6 m 4.23 m 4.01 m 4.28 m 4.28 m
0.31 m 0.31 m 0.31 m
Hypothesis :1 – European legislation2 – No security constraints
Design is still evolving, it should be not far from :
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 3
RFQ MAIN PARAMETERS
Main parameters :Technology : 4-vanes,Length : 3.85 mEnergy range : 0.020 – 1.3 MeV/uVoltage : V = 70 kV (D+) < 1.6 KpAverage radius : R > 4 mmPole modulation : m < 2
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 4
RFQ ACCEPTANCE AT RFQ ENTRANCE
RFQ Acceptance : phase-spaces region at RFQ entrance where a particle can survive (exit with the nominal energy) a transport through the RFQ
Pink : 0 mA acceptance Green : 5 mA acceptanceMulticolor : Beam at RFQ entrance
Injected beam (including tails to ±4 s) close to the RFQ acceptance
RFQ entrance Associated RFQ exit
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 5
RFQ – NOMINAL BEAM DYNAMICS – 5.1 MA
Deuterons (70 kV) Protons (50 kV)
Deuterons :- Transmission : 99.3 %- Emit T : 0.202 p .mm.mrad- Emit L : 31.8 p .°.keV/u- Halo T : 0.99- Halo L : 1.66
Protons :- Transmission : 99.0 %- Emit T : 0.204 p .mm.mrad- Emit L : 37.3 p .°.keV/u- Halo T : 1.05- Halo L : 1.87
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 6
MEBT FUNCTIONS
The fast chopper system has been based on what has been achieved for SPIRAL2 (@ 88MHz) and Linac4 (@352 MHz) :- A conservative ±800 V voltage switched in less than 4.5 ns, between 790 mm plates,
• SPIRAL2 : ±2000 V in 9 ns between 272 mm long plates,• Linac4 : ±650 V in 2.0 ns between 800 mm long plate.
- The plates will be placed in a doublet of quadrupoles. - The beam transport from deviator to beam stop is inspired by this used on Linac4.- The 1.3 kW beam stop is 650 mm long (400 mm for SP2 @ 7.5 kW)
- Match the beam from the RFQ to the SCL,- Diagnose the beam,- Clean the beam,- Stop the beam,- Leave room to host a fast chopper system in future.
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 7
MEBT DESIGN
SCLentrance
RFQinsideexit
Q1RB1
Q2 Q3 Q4
|262|130 |130
|62 |35|240
|35|130 |350
Q5 Q6 Q7 Q8 Q9RB2 RB3
|130 |130|62
|130|35
DB1
|25 |25|450 |130
|100|240
|100|130 |130 |130
|62 |35|240
Chopper plates
DB2|35
0 327 519 739 959 1151 1481 2111 2396 2881 3851 4043 4263 4733
SB1 SB2
|70|130
|30|30|650/520
Chopper stopper SB3
|130
9 SPIRAL2-type quadrupoles 3 three-gap bunchers
3 sets of H/V slits
2 diagnostics boxes for current, position, profile, emittance measurements.
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 8
FC SEPARATION
SCLentrance
RFQinsideexit
Q1RB1
Q2 Q3 Q4
|262|130 |130
|62 |35|240
|35|130 |350
Q5 Q6 Q7 Q8 Q9RB2 RB3
|130 |130|62
|130|35
DB1
|25 |25|450 |130
|100|240
|100|130 |130 |130
|62 |35|240
Chopper plates
DB2|35
0 327 519 739 959 1151 1481 2111 2396 2881 3851 4043 4263 4733
SB1 SB2
|70|130
|30|30|650/520
Chopper stopper SB3
|130
Good separation@ 800 V
A good separation could be achieved even with low (800 V) voltage.
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 9
MEBT ZERO CURRENT ACCEPTANCE
SB1
SB1
SB2
SB2SB3
SB3
MEBT Acceptance : phase-spaces region at RFQ exit where a particle can survive (exit with the nominal energy) a transport through the MEBT
Slits are well positioned and phase-space area can be precisely cut.
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 10
SCL (JANUARY DESIGN)
Main parameters :4 cryomodules,4.23+4.01+2×4.28+3×0.31 = 17.7 m.
CM1 CM2 CM3 CM4
13 low-beta (0.091) cavitiesEaccmax = 7 MV/m
12 high-beta (0.194) cavitiesEaccmax = 8.1 MV/m
16 SC solenoids16 BPM
4.23 m 4.01 m 4.28 m 4.28 m
0.31 m 0.31 m 0.31 m
b=0.052 b=0.206b=0.084 b=0.117 b=0.163b=0.052 b=0.285b=0.104 b=0.153 b=0.233
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 11
NOMINAL BEAM DYNAMICS
Nominal :
From RFQ entrance to SCL exit,
Input distribution: matched, gaussian (H=1), ±4 s, 0.2 p.mm.mrad (rms, norm.)
Particles (P): Deuterons – Protons
Currents (I): 0.1 – 5.1 mA
Final energies (E): 1.3 MeV/u – 40 MeV
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 12
NOMINAL: DEUTERONS – 5 MA – 40 MEV
10-5
6.612.9
25.5
41.0
3
Less apparent margins at CM1-CM2 transition
< 25 %
~ Optimum fields
> 40 MeV
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 13
NOMINAL BEAM DYNAMICS – SUMMARY
P-I-E D-5-40 P-5-40 D-0.1-40 D-0.1-40 D-5-1,3
Energy [MeV] 41.0 40.7 40.2 40.6 2.6
Emit.T [p.mm.mrad] 0.22 (0.20) 0.23 (0.20) 0.22 (0.20) 0.23 (0.20) 0.20
Emit.L [p.°.keV/u] 31.5 (31.8) 41.2 (37.3) 49.4 (47.4) 57.5 (53.4) 56 (cw)
Halo.T 1.22 (0.99) 1.36 (1.05) 1.23 (1.00) 1.59 (1.01) 0.98
Halo.L 2.18 (1.66) 1.83 (1.87) 1.07 (0.84) 1.11 (0.83) 3.53 (cw)
Beam dynamics results summary :
Emittance and halo are under control
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 14
0 1 2 3 4 5 6 7 8 9 10
10-4
10-3
10-2
10-1
100
101
Distance to center normalised to RMS
Den
sity
nor
mal
ised
to in
tegr
al
uniformparabolicgaussianexponentialBennett
HALO PARAMETER ILLUSTRATION
H = 0H = 0.25H = 1H = 3H = 4.7
The higher the halo parameter, the larger/denser the tails
Halo parameter : ratio between 4th and 2nd order momentum in 2D phase-spacecentered and normalized to : 0 – for uniform distribution
1 – for gaussian distribution
(truncated to 10s)
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 15
ERRORS STUDIES : AMPLITUDES
Error type Static Dynamic
x [mm] ±0.2 ±0.010
y [mm] ±0.2 ±0.010
x [°] ±0.1 ±0.005
y [°] ±0.1 ±0.005
z [°] ±1 ±0.05
G/G [%] ±1 ±0.05
Error type Static Dynamic
x [mm] ±0.5 ±0.01
y [mm] ±0.5 ±0.01
x [°] ±0.12 ±0.005
y [°] ±0.12 ±0.005
E/E [%] ±1 ±0.1
[°] ±1 ±0.1
Error type Static Dynamic
x [mm] ±1 ±0.02
y [mm] ±1 ±0.02
x [°] ±0.5 ±0.01
y [°] ±0.5 ±0.01
z [°] ±1 ±0.1
G/G [%] ±1 ±0.05
Error type Static Dynamic
x [mm] ±1 ±0.02
y [mm] ±1 ±0.02
x [°] ±0.5 ±0.01
y [°] ±0.5 ±0.01
E/E [%] ±1 ±0.1
[°] ±1 ±0.1
MEBT quad MEBT rebunchers
SCL solenoids SCL cavities
1000 linacs, 510 000 particles at RFQ input equivalent to 5 108 particles
Static errors corrected (only) with steerer-BMP correction schemeEuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 16
ERRORS STUDIES : EMITTANCE AND HALO
Emittance and halo histograms
Emittance growth (compared to nominal) :Average : < 5.5%(T); < 2%(L)90% : < 12%(T); < 7% (L)
Final Halo parameter (nom. : 1.22) :Average : < 1.2690% : < 1.4 A little more halo in y (due to MEBT).
Low halo and emittance production
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 17
ERRORS STUDIES : PROBABILITIES
Probability density
For example :The 10-7 line represents the radius of a cylinder outside which one can find :10-7×1000×510000 = 51 particles in all simulations
TLR limit (/m)
Lower margins at CM3-CM4 transition
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 18
ERRORS STUDIES : LOSS ESTIMATION
Losses per CM estimation
20 particles lost
Lower margin in CM3
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 19
CONCLUSION
- RFQ acceptance of about 5 p.mm.mrad (~± 5 s @ 0.2 p.mm.mrad)
RFQ : good initial beam scraper, good transmission @ 0.2 p.mm.mrad
- MEBT with room for fast chopper, diagnostics and slits
- 5 nominal simulations (Deuteron/Proton; 0.1-5 mA; 1,3 MeV/u-40 MeV)
- Error study for more “sensitive” conditions (Deuterons, 5 mA, 40 MeV)
Satisfying TLR
Satisfying TLR
- A new reference design (more robust) in progress
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 20
NEW CONFIGURATION (LAST TUESDAY)
EuCARD-MAX workshop at CERN | March 20th 2014 | PAGE 21
4.59 m
12.5 MeV7.3 MeV2.6 MeV
27.2 MeV 44.2 MeV
5.00 m 5.00 m
4.59 m
b~0.185b=0.091
12.9 MeV 25.5 MeV 41.0 MeV
4.28 m
6.6 MeV2.6 MeV
4.01 m4.23 m
4.28 m
b=0.091 b=0.194
PD
R