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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