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Moriond Meeting 17-21/3/2003. Contents. Acceleration of RIB using linacs. Introduction Technological highlights in superconducting low-  l inacs Superconducting linacs for RIB acceleration Example of multicharge transport in EURISOL SRL Conclusions. Alberto Facco

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contents

Moriond Meeting 17-21/3/2003

Contents

Acceleration of RIB using linacs

  • Introduction
  • Technological highlights in superconducting low- linacs
  • Superconducting linacs for RIB acceleration
  • Example of multicharge transport in EURISOL SRL
  • Conclusions

Alberto Facco

INFN-Laboratori Nazionali di Legnaro

ideal rib accelerator requirements

Moriond Meeting 17-21/3/2003

Ideal RIB accelerator requirements
  • Acceleration of all possible radioactive beams
  • All possible final energies up to ~ 100 MeV/u, finely tuneable
  • Capability of acceleration of singly charged ions
  • Very good beam quality up to at least 10 MeV/u
  • Affordable construction and operation cost
  • reliability, easy maintenance, easy beam set-up and operation, etc.
rib accelerators special constraints

Moriond Meeting 17-21/3/2003

RIB accelerators special constraints
  • Variable q/A beams
    • Efficiency in a wide range of q/A
    • Wide acceptance in : acceleration with variable velocity profiles is desirable
  • Very low current beams
    • negligible beam loading: Rf power efficiency
    • Stability and large acceptance
    • Very high transmission efficiency, aiming to 100%
independently phased superconducting cavity linacs virtues

Moriond Meeting 17-21/3/2003

Independently-phased Superconducting Cavity Linacs virtues
  • Wide velocity and q/A acceptance
  • Modularity: all final energies can be reached, with fine tunability
  • Excellent beam quality
  • Transmission efficiency limited only by charge selection after stripping

Recent achievements in the field:

high transmission efficiency after stripping

Competitive construction and operation cost

Multicharge beam transport

High acceleration gradient

slide6

Moriond Meeting 17-21/3/2003

Superconducting QWR’s

(optimum range 0.03<<0.3 and 50<f<200 MHz)

Mechanical damper

LNL 80 MHz, =0.055 cryostat

Best ALPI and PIAVE

low beta cavities results

LNL PIAVE 80 MHz,  =0.047 QWR

slide7

Moriond Meeting 17-21/3/2003

ISAC-II =0.072 cavity

  • Design gradient: 6 MV/m @7W
  • reached 7 MV/m with <10W

TRIUMF ISAC-II 106 MHz, =0.072 prototype

4.2 k test results

slide8

Moriond Meeting 17-21/3/2003

Superconducting Spoke resonators

(optimum range 0.2<<0.5 and f350 MHz)

ANL =0.3 and = 0.4

prototypes

LANL =0.2 prototypes

slide9

Moriond Meeting 17-21/3/2003

Superconducting RFQ’s

  • Compactness
  • CW operation
  • High efficiency

LNL Superconducting SRFQ2

A/q=8.5,

0.0255<b<0.0355

6 mv m already achieved in existing linacs 7 mv m seems very realistic for future accelerators

Moriond Meeting 17-21/3/2003

6 MV/malready achieved in existing linacs7 MV/mseems very realistic for future accelerators

Low - SC linacs design gradient

em steering in qwr s

Eurisol Town Meeting, Abano 24-25/1/2002

EM steering in QWR’s
  • The steering is proportional to the energy gain
  • The magnetic contribution is dominant
quarter wave resonators with dipole correction

A. Facco - SPES meeting –LNL 11-3-2003

Quarter Wave Resonatorswith dipole correction
  • ANL QWR 115 MHz for RIA
  • MSU QWR 161 MHz for RIA
  • (MSU-LNLcollaboration)

QWR steering :

161 MHz standard shape (top)

161 MHz corrected

slide13

Moriond Meeting 17-21/3/2003

Multicharge beam transport

  • Proposed and demonstrated at ANL (in ATLAS)
  • Studied at
    • ANL and MSU for RIA (driver and reaccelerator linacs)
    • TRIUMF for the ISAC-II reaccelerator
    • LNL for the Eurisol reaccelerator
  • Important tool to achieve high efficiency in both transmission and acceleration
slide14

W

q1

q2

q3

q4

f

Moriond Meeting 17-21/3/2003

Multicharge beam transport

  • Ions with different charge state receive the same acceleration if their synchronous phase is properly chosen
  • Many different charge states can be transported simultaneously
  • Most of the beam particles can be captured after stripping

DW=qEaLT(b)cosf

slide15

F=-150

F=-150

F=-1000

F=-200

beam

Phase synchronization after the first stripper, at the beginning of the SRL ME section. Top: first cryostat (see fig 3) and the reference acceleration phase at each of the cavities. Bottom: longitudinal phase space, in energy spread (%) as function of phase (deg) in different position along the cryostat. The cavities frequency is 160 MHz. The 5 charge states of the beam particles are represented by different colors.

Moriond Meeting 17-21/3/2003

Multicharge beam transport

slide16

Moriond Meeting 17-21/3/2003

Examples of superconducting linacs for RIB acceleration

isac post accelerator at triumf operating under completion

Moriond Meeting 17-21/3/2003

ISACpost-accelerator at TRIUMF(operating, under completion)
  • ISAC-I, in operation
  • NC Linac up to 1.5 MeV/u
  • ISAC-II, under construction
  • SC linac ~43 MV
  • Rib energy up to ~6 MeV/u
  • A150
  • 1 or 2 carbon foil strippers
  • Multicharge transport
  • Charge breeder for A>30
isac post accelerator special components

Moriond Meeting 17-21/3/2003

ISACpost-accelerator special components
  • 35.3 MHz RFQ A/q 30 (8m long)
  • 106 MHz Separate function DTL
  • SC QWRs
  • 70.7 MHz =0.042
  • 106 MHz, =0.072 (under construction)
  • 106 MHz =0.105

ANL-RIA type SC solenoids

Inside cryostats

the ria rib facility

Moriond Meeting 17-21/3/2003

The RIA RIB facility
  • RIA Driver SC linac:
  • Ion beams of all masses
  • 400 MeV/u Uranium

RIA driver superconducting cavities under development at ANL

RIA (MSU version)

the anl ria post accelerator proposed as injector of the existing atlas sc linac

Moriond Meeting 17-21/3/2003

The ANL-RIA post-accelerator(proposed as injector of the existing ATLAS SC linac)
  • No charge breeder, accepting q=1+
  • Masses 66<A< 240 need He gas stripper at ~10 keV/u to reach A/q66
  • Carbon foil stripper at 600 keV/u to reach A/q8.3
  • 3 NC RFQs (2 on a 400 kV platform)
  • 62 SC cavities + SC solenoids
  • Output energy 1.4 MeV/u
  • Very efficient in transmission, >30% up to the 2nd stripper
  • Good emittance
  • Very conservative design gradient
  • Beam injected into ATLAS ( ~50 MV)
ria post accelerator special components

Moriond Meeting 17-21/3/2003

RIA post-accelerator special components
  • R&D in an advanced stage for RFQ and SC solenoids
  • 4-gap SC cavity technology well established
  • ATLAS working since 20 years

15 T superconducting solenoid with steerers

4 gap superconducting QWR

12 MHz Hybrid rfq

eurisol srl preliminary project

Moriond Meeting 17-21/3/2003

EURISOL SRL(preliminary project)
  • 2 intermediate stripping stations to increase linac efficiency and reduce linac length
  • 3 main extraction lines for low, medium and high energy experiments
  • Multicharge beam transport to maximize transmission up to 100 MeV/u
  • Acceleration with no stripping and full intensity up to 60 MeV/u
srl cavity parameters

Cavity type

QWR

QWR

QWR

QWR

HWR

units

f

80

80

160

240

320

MHz

b0

0.047

0.055

0.11

0.17

0.28

Ep/ Ea

4.89

 4.81

 4.93

 5.17

 3.7

Hp/Ea

 103

 101

 108

 110

106

Gauss/(MV/m)

G= Rs Q

 14.9

 14.9

 28.3

 38.4

 61.7

W

Rsh/ Q

 1640

1660

1480

 1470

1200

W/m

U/ Ea2

0.121

0.120

 0.0670

 0.0452

 0.093

J/(MV/m)2

Eff. length

0.18

0.18

0.18

0.18

0.223

m

Design Ea

7

7

7

7

7

MV/m

Cryo power allowed

10

10

10

10

10

W

n. required

3

15

24

37

160

Moriond Meeting 17-21/3/2003

SRL cavity parameters

QWR

HWR

  • * Calculated by means of the code HFSS
srl modules

Moriond Meeting 17-21/3/2003

SRL modules

Schematic of RFQ section and first QWR module

SRFQ section

  • 3 LNL type superconducting RFQ’s in 2 cryostats
  • Design A/q  10 (up to 132Sn13+)
  • Ein =2.3 keV/u, Eout =670 keV/u

QWR-HWR modules

  • Cryostat
    • 4 QWR’s (section I and II) at 7 MV/m
    • 8 HWR’s (section III) at 7 MV/m
    • 1 superconducting solenoids at B<15 T
  • Diagnostics box
slide26

Moriond Meeting 17-21/3/2003

Beam dynamics simulations in SRL*

  • Simulation of the accelerating sections
  • using realistic EM fields of QWR’s
  • Aims:
  • Check multiple charge beam transport at high gradient
  • Check the effect of QWR steering in MCBT
  • Evaluate SRL performance in different operation modes
    • No stripper up to 60MeV/u
    • 1 stripper 93
    • 2 strippers 100
  • * performed using the code LANA (courtesy of D. Gorelov, MSU-NSCL)
slide27

Moriond Meeting 17-21/3/2003

Linac Beam Envelopes with no strippers

Simulated using the LANA code

132Sn

Win= 670 keV/u

Wout= 59.6 MeV/u

f = -20 deg

Eacc= 7 MV/m

N.B. simulation performed with an input transverse emittance 2 times larger than the nominal value

high energy section 160 hwr s 1 stripper mode

Moriond Meeting 17-21/3/2003

High Energy Section-160 HWR’s (1 stripper mode)

INITIAL*

FINAL

Simulated using the LANA code

  • 132Sn
  • Win= 16.3 MeV/u
  • Wout= 92.9 MeV/u
  • = -20 deg

q=45,46,47,48,49

  • Eacc= 7 MV/m
  • Eff.= 94%

BUNCHED

* After stripping in a 2 mg/cm2 carbon foil

N.B. simulation performed with an input transverse emittance 2 times larger than the nominal value

linac beam envelopes with 2 strippers

Moriond Meeting 17-21/3/2003

Linac Beam Envelopes with 2 strippers

Simulated using the LANA code

132Sn

Win= 670 keV/u

Wout= 100 MeV/u

f = -20 deg

Eacc= 7 MV/m

N.B. simulation performed with an input transverse and longitudinal emittance 2 and 5 times larger than the nominal value, respectively

high energy section 160 hwr s 2 stripper mode

Moriond Meeting 17-21/3/2003

High Energy Section-160 HWR’s (2 stripper mode)

INITIAL*

FINAL

Simulated using the LANA code

  • 132Sn
  • Win= 21.6 MeV/u
  • Wout= 100 MeV/u
  • = -20 deg

q=46,47,48,49

  • Eacc= 7 MV/m

BUNCHED

* After one more stripping in a 3 mg/cm2 carbon foil

slide31

Moriond Meeting 17-21/3/2003

SRL simulations results for different modes of operation

  • No stripping (prob. most experiments)
    • E max 60 MeV/u
    • Transmission 100% Single charge beam
    • exey  0.5(0.25)p mm mrad, ez  0.7 p keV/u ns (5 rms)
  • Stripper 2 only
    • E max 93 MeV/u
    • transmission 94% Multiple charge beam
    • exey  0.6(0.3)p mm mrad, ez  1.4 p keV/u ns (5 rms)
  • Strippers 1 and 2
    • E max 100 MeV/u
    • Transmission 74% Multiple charge beam
    • exey  1(0.5)p mm mrad, ez  10(2)p keV/u ns (5 rms)
  • N.B: 2 Strippers make the linac relatively insensitive to the charge breeder performance: with initial charge of 13+ instead of 25+, the final energy would be 95 MeV/u
slide32

Moriond Meeting 17-21/3/2003

Acceleration of different q/A beamswith 2-gap cavities

Virtually all RIB’s that allow charge breeding can be accelerated by SRL with similar results.

Examples:

  • 33Ar(8+)

E=127 MeV/u

  • 210Fr(25+)

E=100 MeV/u

33Ar(8+)

210Fr(25+)

conclusions

Moriond Meeting 17-21/3/2003

Conclusions
  • Recent developments in SC linac technology

multiple charge beamtransportbeam stripping and high transmission

Superconducting cavites high gradients, wide b acceptance

  • High charge breeding is not strictly necessary
    • (but some charge breeding saves a lot of money)
  • SC linacs can provide
    • RIB acceleration with finely tuneable energy and good beam quality
    • High acceleration and transmission efficiency
    • Large acceptance in q/A low mass selectivity, but also

low sensitivity to charge breeder performance

    • flexibility in the modes of operation
    • competitive construction and operation cost

SC linacs can be excellent RIB accelerators

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