BEAM TRANSFER CHANNELS, BEAM TRANSFER CHANNELS, INJECTION AND EXTRACTION SYSTEMS OF NICA ACCELERATOR...

BEAM TRANSFER CHANNELS,

INJECTION AND EXTRACTION SYSTEMSOF NICA ACCELERATOR COMPLEX

Tuzikov A.,JINR, Dubna, Russia

NICA beam transfers

Beam transfer from HILAC to Booster

• HILAC-Booster transport channel;• Booster injection system.

Beam transfer from Booster to Nuclotron

• Booster fast extraction system;• Booster-Nuclotron transport channel;• Nuclotron high energy beam injection system.

Beam transfer from Nuclotron to Collider

• Nuclotron fast extraction system;• Nuclotron-Collider transport channel;• Collider injection system.

2NICA MAC 2015

Beam transfer from HILAC to Booster

Goals

•Accumulation of required intensity of ions in Booster by means of several methods of beam injection.

Beam parametersSort of ions Au31+ (Au51+, Au65+)Energy, MeV/u 3.2Magnetic rigidity, T m 1.6Electric rigidity, MV 40Ion number 2∙109

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HILac

Booster

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• The beam transport with minimal ion losses.• The beam debunching.• The beam matching.• Separation and adsorption of neighbor

charge states of ions.• Providing different schemes of the beam

injection into the Booster.

Main goals

HILAC-Booster beam transport channel

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IES

• Length of first straight line of the channel? The debuncher should be located in non-dispersive region.

• Angle between final straight line of the channel and 1st straight line of Booster? There are two concurrent tasks: to minimize length of electrostatic septum of Booster injection system and to minimize final ‘dead zone’ of the channel.

Optimization of the channel geometry

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Channel geometry

Whole channel Part inside Synchrophasotron yoke


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Parameters of main elements

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Q1 Q2 Q3 Deb. BM2 Q7 Q8 Steer.

Available at JINR

Q4 Q5 Q6BM1

Magnetic element Dipole Quadrupole

Effective length, m 0.647 0.29

Max field (gradient), T (T/m)

1.21 10

Gap (diameter), mm 76 95

Debuncher

Designed by Bevatech team

Inner length, m 0.49

Frequency, MHz 100.625

Max effective voltage, kV

340

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1 2 4

1) Betatron matching of the beam with Booster lattice functions (section 1-2).2) Matching of horizontal dispersion of the beam with Booster (section 2-4).3) Focusing of the beam to avoid ion losses inside the debuncher (section 1-2).4) Vertical focusing of the beam to avoid ion losses inside dipoles (section 1-3).5) Separation of charge states of ions (section 1-3).

Concept of optical system tuning

Q1 Q2 Q3 Deb. BM2 Q7 Q8 Steer.Q4 Q5 Q6BM13

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Horizontal dispersion


Beta functions

Beam dynamics simulations

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• The beam injection with minimal ion losses.• The beam injection by the following methods:

single-turn injection, multiturn injection, multiple injection.

Goals

Booster injection system

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• Accumulation of ions in horizontal phase plane.• Closed orbit bump (for multiturn and multiple

injections).• Rapid change of fields in the system elements

(for more compact filling of the horizontal phase plane in case of multiturn and multiple injections).

Features

1st straight section

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Parameters of elements

Length, m Gap, mm X1, mm X2, mm Max voltage, kV

IK1 0,5 102 -51 +51 40

IK2 0,8 93 -36 +57 40

IK3 0,5 102 -51 +51 60

IES 2 35 [+40; +205] [+75; +240] 120


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IK1 IES IK2 IK3

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Injection electrostatic septum IES

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Electric injection kickers IK1 – IK3

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Goals

•Transfer of the beam with parameters which can be altered in wide ranges due to 1) use of different schemes of beam injection into Booster and 2) use of an electron cooling system.

•Ion stripping to a maximum charge state.

•Control of the beam emittances.

Sort of ions:

before stripping station

after stripping station

Au31+ (Au51+, Au65+)

Au79+

Maximum energy of ions inside the channel, MeV/u 685Maximum magnetic rigidity of ions inside the channel, T m:

before stripping station

after stripping station

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11

Ion number 1.5∙109

Beam Parameters

Beam transfer from Booster to Nuclotron

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Booster

Nuclotron

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• Fast extraction of the beam with minimal ion losses.

Goals

Booster fast extraction system

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• Closed orbit bump (for required kick’s minimization).

Features

Kicker

Magnetic septum

3rd straight section

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Length, m 3

Max magnetic field, T 0.13

Aperture, mm×mm 80×90

Pulse duration, μs: rise plateau fall

0.250.5~10

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Kicker

Length, m 2.5

Max magnetic field, T 1


Septum thickness, mm

3

Pulse shape semisinusoidal

Pulse duration, μs ~ 10

Septum

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Kicker

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40м

м

d=80мм

beam

Extracted beam area

Injected beam area

Magnetic field (T): measurements

Magnetic field (T): simulations Magnetic field homogeneity


Kicker

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Septum

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The current-carrying plate and the shield Lines of force

Magnetic field (T) Surface current density (MA/m).


Septum

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Magnetic field distribution along vertical line Magnetic field distributions along horizontal line

Septum


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Magnetic field distribution between the plate and the shield: simulations and measurements

Magnetic field distributions along longitudinal line

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Goals

Booster-Nuclotron beam transport channel

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• The beam transport with minimal ion losses.• Ion stripping to the maximum charge state.• Separation of neighbor charge states. Estimates of ion stripping at energy of 580

MeV/u: 100% Au31+ → 80% Au79+, ~20% Au78+. Due to high intensity of Au78+ ions they have to be extracted from the channel to an absorber.

• Minimization of emittance growth and control of emittances of the beam injected into Nuclotron.

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Channel geometry

View from above

Vertical profile

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Preliminary parameters of magnetic elements

Magnetic element

Type Effective length, m

Max. magnetic field (gradient), T (T/m)

BM1 – BM4 sector dipole 1.7 1.8

LM Lambertson magnet 1.5 1.5

Q1, Q2 quadrupole 0.6 30

Q3 – Q6 quadrupole 0.4 20

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Generalized optimization of optical system

• Multiple scattering and energy straggling of ions at the stripping target.• Coupled motion in tilt bending magnets.• Mismatch of the beam with Nuclotron.

Transverse and longitudinal emittance growth

1) Minimum growth of emittances after the beam filamentation inside Nuclotron.2) Criteria of transverse emittances’ control: for example, equality of horizontal and vertical emittances to each other.3) Full separation of Au78+ ions from the Au79+ beam at the entry of the Lambertson magnet. 4) Minimum beam sizes along the channel.5) Criteria of quadrupole gradients’ control: for example, minimization of gradients.

Criteria of optimality

There are optimal settings of the optical system (i.e. optimal gradients of the quadrupoles) for any working regime (initial parameters of a beam). But it is not for practical use.

Ways to reduce number of independent variables and number of working regimes:1) Use of one setting for many working regimes.2) Use of settings which are not optimal but close to global optimum.

Concept of optical system tuning

NICA MAC 2015

• Single-turn injection of the beam with minimal ion losses.

Goals

Nuclotron high energy beam injection system

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Length, m 3




~100.50.25

Kicker

Length, m 1; 1.5; 0.5

Max magnetic field, T 1.2; 1.2; 1


15; 15; 5

Power supply system cyclic, cycle duration ~1 s

Lambertson magnet (three sections)

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Beam transfer from Nuclotron to Collider

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Goals•Alternate filling of the

Collider rings.•Accumulation of required

intensity of ions (with help of barrier bucket system and beam cooling systems of Collider).

Sort of ions Au79+

Energy of ions, GeV/u 1 ÷ 4.5Magnetic rigidity of ions, T m

14 ÷ 45

Ion number 1∙109

Beam Parameters

NICA MAC 2015

• Fast extraction of the beam with minimal ion losses.

Goals

Nuclotron fast extraction system

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Length, m 3




≤ 0.2≥ 0.2~10

Kicker

Length, m 0.5; 2.5

Max magnetic field, T 1; 1.6


5; 10

Power supply system cyclic, serial to dipole magnets

Lambertson magnet (two sections)

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Goals

Nuclotron-Collider beam transport channel

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• The beam transport with minimal ion losses.• The beam matching with lattice functions of the Collider rings except vertical

dispersion which suppression is sufficient.

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Parameters of pulsed magnet elements


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Magnetic element Number Effective length, m Max. magnetic field (gradient), T (T/m)

Horizontal bending magnet

19 2 1.5

Vertical bending magnet 12 2 1.5Correcting bending

magnet2 1 1.5

Quadrupole 45 0.5 20

Designed by BINP team

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Vertical dispersion suppression


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Suppresion vs matching• Vertical dispersion is not fully suppressed in Collider. Value of the dispersion in the beam

injection point is equal to 0.03 m.• If the beam is injected with zero dispersion then the beam emittance grows due to phase

density filamentation. But this effect is negligibly small.

How to suppress vertical dispersion• The best solution is to provide achromatic transfer of the beam from Nuclotron to median

planes of the Collider rings in the common part of the channel. But lattice variants which meet condition of achromatic transfer have not been found.

• Vertical dispersion can be suppressed by means of optical sections with vertical bending magnets located in branches of the channel. The most preferable locations of dispersion suppressors are long straight sections of the channel branches.

What if vertical dispersion will not be suppressed• Since vertical dispersion suppressors make the channel lattice too complex, lattice without suppressors is proposed as an alternative.• Beam dynamics simulations have shown that vertical emittance growth due to unsuppressed dispersion does not exceed 10%.

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Variant 1 of vertical dispersion suppression


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• Minimization of vertical dispersion invariant () at the exit of the common part of the channel is critical.• Low values of vertical beta functions are required inside suppressors.

Common part

Dispersion suppressor

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Variant 2 of vertical dispersion suppression


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• Minimization of vertical dispersion invariant at the exit of common part of the channel is optional.• There are no limitations on values of vertical beta functions inside suppressors. Vertical dispersion suppression is provided by tuning betatron phase advance between parts of the suppressors.

Common part

Dispersion suppressor

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Optical system


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Tuning of optical system • Section E-C1: minimization of .• Sections C1-L1 and R1-R2: matching of , and ; suppression of .• Sections L1-LI and C1-R1: matching of horizontal dispersion invariant .• Section R2-RI: minimization of .

NICA MAC 2015

Length, m 4.6



Pulse duration, ns: total plateau

< 900150-200

Kicker


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Collider injection system

Length, m 1.5

Max magnetic field, T 1



3

Pulse shape semisinusoidal

Pulse duration, ms ~ 10

Septum

• Single-turn injection of the beam with minimal ion losses.

Goals

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THANK YOU FOR ATTENTION

Additional slides


Power supplies

Pulse

Trise < 50 ms

Tpl 8 ÷ 30 µs

Tfall ≤ 0.1 µs

IK1 IK2 IK3

Plate №1 Plate №2 Plate №1 Plate №2 Plate №1 Plate №2

40 kV 0 kV 40 kV 15 kV 60 kV 15 kV

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Impulse on plate №1

Difference impulse

U

t

Upl,1

U

t

Upl,2

U

t

Upl,1

- Upl,2

T1st pl

T2nd pl

Trise

Upl,1

Impulse on plate №2

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• Beam duration – less than 8.5 µs.• Horizontal emittance – 15 ÷ 160 π·mm·mrad.• Vertical emittance – 15 π·mm·mrad.

Voltage, kV Electric field, kV/cm Angle, mradIK1 0 0 0

IK2 0 0 0

IK3 37 ÷ 54 3.6 ÷ 5.3 4.7 ÷ 6.8

Main injection method and its modification

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Concept of multiturn injection

•Accumulation of ions during several periods of the beam revolution.•Horizontal emittance of stored beam depends on number of turns and horizontal

betatron tune.•Horizontal emittance for different injection schemes – 65 ÷ 120 π·mm·mrad.

3

0,1,2

3

septum

X

X’

3 1,2

2

0,1,2

3

2

0,1

2

septum

X

X’

1

0

1

2

Double-plateau pulseSingle-plateau pulse

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Concept of multiple injection•Accumulation of ions by multiple repetitions of single-turn injections.•Varying the horizontal phase portrait of the injecting beam allows more compact filling of the phase

plane. •Horizontal emittance of the stored beam depends on number of injection repetitions.•Horizontal emittance for different injection schemes – 50 ÷ 135 π·mm·mrad.

Double-plateau pulseSingle-plateau pulse

1

0

septum

X

X’

0

1

1

< 0

1

0

septum

X

X’

0

0

1

1

< 0

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Closed orbit bump

Beam extraction

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Beam dynamics example: single turn injection into Booster; no beam cooling

• Initial horizontal emittance εx,0 (r.m.s.): 0.14 π∙mm∙mrad. • Initial vertical emittance εy,0 (r.m.s.): 0.14 π∙mm∙mrad.• Initial momentum spread σp,0 (r.m.s.): 3∙10-4.• Stripper target: carbon, thickness 125 μm.

Working regime of the channel

Lattice functions

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Beam dynamics example

Separation of Au78+ ions

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Magnetic elements

Nuclotron high energy beam injection system

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Beam injection

Kicker Lambertson magnet (three sections)

?

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Collider injection system

Kicker with correcting unit

Magnetic fields in kicker units Effective magnetic field acting on ions

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Beam extraction

Nuclotron fast extraction system

NICA MAC 2015

BEAM TRANSFER CHANNELS, BEAM TRANSFER CHANNELS, INJECTION AND EXTRACTION SYSTEMS OF NICA ACCELERATOR...

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