Injection to IOTA ring

Sergey Antipov, University of Chicago

Fermilab Mentor: Sergei Nagaitsev

Injection to IOTA ring

Integrable Optics Test Accelerator

Proof-of-principle experiment designed to demonstrate a concept of integrable accelerator lattice with highly non-linear optics.

Demonstrate that huge nonlinear tune shifts can be achieved in a realistic accelerator design

My part: Design injection part of the ring and conduct first-stage experiments with non-linear optics

ASTA linac

ParameterValueEnergy150 MeVNumber of e in bunch109Circumference40 mBending dipole field0.7 TRF voltage50 kVMax x, y9 m, 4 mMin x, y0.1 m, 0.25 mMomentum compaction0.14Betatron tuneQx,Qy = 3.2 (2.4 to 3.6)Equilibrium transverse emittance0.06 m (non-normalized)Synchrotron damping time~ 1 s

Energy150 MeVEmittance, normalized5 m-functions~ 100 cmRMS beam size~ 0.2 mmPhysical aperture50 mmBend angle15 deg

Lattice functions

RMS beam size

Injection section

Optics designed by Gene Kafka

Optics is flexible

Optics designed by Gene Kafka

Integrable Optics

Optical Stochastic Cooling

Summary of requirements

Single turn injection (No storage needed)

Should suit both integrable optics and optical stochastic cooling lattice designs

Injection kicker should be able to work for experiments

Proton injection?

Components:

Beam transmission line

Septum magnet

Fast kicker

Local orbit bump (if any)

Injection procedure. Orbit bump is not shown

Single turn injection

Kick:

Plan

Choose a design of injection magnet

Determines separation of orbits

Locations of magnet and kicker

Beta-functions

Kick angle

Design of kicker

Voltage

Transmission line

Should provide matching (, , D, D`)

Septum magnet

Place particles onto the correct trajectory

Bend ~ 15 deg.

Installed in high-beta region to reduce the kick

Options:

Can be DC (heating might be an issue) or pulsed (stability might be an issue)

Current sheet isolation or Lambertson

Septum design

Current sheet isolation

Lambertson

Injection in horizontal plane

Possible problems with field leakage

Septum thickness determined by max current density

Pulsed device

Injection in vertical plane

A bigger (more expensive) device

Septum thickness

Can be DC

DC Lambertson septum

DC offers higher stability than pulsed devices

Lambertson septum has simpler design

Gap increased to fit for proton injection

Power consumption ~ 1.5 kW

Beam separation:Septum thickness 2mm +thickness of vacuum chambers +reserve -> ~ 10 mm

ParameterValueBend angle15 degBend radius190 cmB-field2.6 kGsLength50 cmGap height2.7 cmCurrent5.6 kASeptum thickness2 mmVertical incline1 degCoil resistance12 mPower consumption1.5 kW

Fast kicker

Stripline

Length:

Separation of plates:

Bend angle:

Pulse duration:

Will be used for nonlinear optics experiment >must have enough power for them

At least 8 mrad

Should have 50 wave impedance

Can fit inside quadrupole magnets

Want wide kicker plates

Vertical E-field as a function of radius for different .Applied voltage 30 kV.Green 45, blue 60, red 80 deg.

Opening angle 80 deg

Greater field in the center

More homogenous field

Probably, need to separate H and V kickers

Up to 30-40 kV can be achieved with solid stateshort pulse generators

Prices on products of Directed Energy

Would require HV DC power supply ( cost not included)

Cost1500350060001000035004500750011500

Peak Voltage, V

Cost, $

Minimizing Vkick

Vary kicker length and position, position of septum, number, strength and position of dipole correctors

Constraints:

Min separation of beams 10 mm

Particles should not hit kicker plates, 2 mm reserve

Orbit of circulating beam should be no closer than 6 to physical aperture

Lengths: septum 50 cm, correctors 15 cm

Length of kicker < 2 m

integrated field of dipole correctors 10 kGs-cm

ParametersOption 1Option 2Beta functions:septumkicker101 cm130 cm100 cm90 cmKick angle16 mrad13 mradKicker length160 cm100 cmKicker voltage (+/-)25 kV30 kVOrbit bump:Number of correctorsCorrector lengthMax integrated field415 cm6.9 kGs-cm315 cm9.5 kGs-cmSeparation of orbits14 mm14 mmDisplacement of point of injection relative to center of straight section20.5 cm162 cm

Option 1. Septum in the center of straight section

Option 2. Septum between pairs of quads

3 size is shown

Voltage 30 kVKicker length120 cmDistance septum-kicker60 cm

Requirements to short pulse generators

Pulse Voltage 0-30 kVPulse flattop30-100 nsRise/fall time20 nsStability5% pulse-to-pulseJitter, trigger-HV pulses or lessRepetition rate0.1 Hz or fasterLoad50 Ohm, resistivePeak current600 APeak power18 MWPower supply110 V, 60 Hz

Need 4 pulsers

~ 100 % reserve for integrableoptics experiments

Final choice of pulse generators willdetermine design of the kicker

What else can be done?

Reduce aperture at septum

Allow to inject with 0 anglewithout hitting kicker plates

1 cm does not affect admittance

Reduce kicker length

No orbit correction?

1 sec synchrotron damping time

Same kick needed

Current and future activity

Contacted manufacturers about quotes for high power short pulse generators

Choice of a generator determines final kicker design

Electric design of stripline kicker

Design of septum magnet

Finalize positions of injection magnet and kicker

Beam line

Thank you for attention

Backup slides

Options for short pulse generators

ManufacturerMontenaIoffeFID GmbhPulse Voltage0-50 kV5-25 kV2.5-25 kVRise/fall time5/10 ns< 20 ns10-12 nsPulse flattop50-100 ns50-100 ns50-100 nsJitter~ 100 ns< 1 ns< 1 nsCommentsElectromechanical switchDouble forming line, fast semiconductor closing switchSolid state switchPriceN/ANo offer yet29 000

Simulating field in kicker

SCT EM Studio

Need:

50 Ohm wave impedance

E < 50 kV/cm at any point

0

1

2

5

10

15

20

25

E

y

r

80

180

p

,

E

y

r

p

3

,

E

y

r

p

4

,

r

V

source

V

k

w

160

,

(

)

2

25.02

=

:=

50

100

150

200

0

20

40

60

16 mrad

8 mrad

Kicker Length, cm

Required power supply, kV