High-Power Targets H.G. Kirk

Harold G. KirkBrookhaven National Laboratory

High-Power TargetsH.G. Kirk

Applications of High-Intensity Proton Accelerators

FNAL

October 20, 2009

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 2

Subject Matter Covered Here

WG1 High-Power Target Issues

WG2 Target Station Design and Requirements for Muon Colliders and Neutrino Factories

Harold G. Kirk


The Challenge: Convert to Secondaries

Intense Primary Beam Intense Secondary Beam

Secondary Beams for New Phyisics Neutrons (e.g. for neutron sources) π’s (e.g. for Super ν Beams) μ’s (e.g. for Muon Colliders, Neutrino Factories) Kaons (e.g. for rare physics processes) γ’s (e.g. for positron production) Ion Beams (e.g. RIA, EURISOL, β-Beams)

Target

Harold G. Kirk


High-power Targetry Challenges

High-average power and high-peak power issues Thermal management

Target melting Target vaporization

Radiation Radiation protection Radioactivity inventory Remote handling

Thermal shock Beam-induced pressure waves

Material properties

Harold G. Kirk


Choices of Target Material

Solid Fixed Moving Particle Beds

Liquid Hybrid

Particle Beds in Liquids Pneumatically driven Particles

Harold G. Kirk


High-Power Targetry R&D

Key Target Issues for high-power targets What are the power limits for solid targets? Search for suitable target materials (solid and liquid) for primary beams > 1MW Optimal configurations for solid and liquid targets Effects of radiation on material properties

Target materials Target infrastructure

Material limits due to fatigue Design of reliable remote control systems

Harold G. Kirk


IronPlug

ProtonBeam

NozzleTube

SC-1SC-2 SC-3 SC-4

SC-5Window

MercuryDrains

MercuryPool

Water-cooledTungsten ShieldMercury

Jet

ResistiveMagnets

Neutrino Factory Study 2 Target Concept

ORNL/VGMar2009

SplashMitigator

NF/MC Target System

Van Graves, ORNL

Harold G. Kirk


A 4MW Target Hall

Phil Spampanato, ORNL

Harold G. Kirk


High-peak Power Issues

When the energy deposition time frame is on the order off or less than the energy deposition dimensions divided by the speed of sound then pressure waves generation can be an important issue.

Time frame = beam spot size/speed of sound

Illustration

Time frame = 1cm / 5x103 m/s = 2 µs

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 10

CERN ISOLDE Hg Target Tests

Bunch Separation [ns]

Proton beam5.5 Tp perBunch.

A. Fabich, J. Lettry

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 11

Pressure Wave Amplitude

Stress = Y αT U / CV

Where Y = Material modulus

αT = Coefficient of Thermal Expansion

U = Energy deposition

CV = Material heat capacity

When the pressure wave amplitude exceeds material tensile strength then target rupture can occur. This limit is material dependant.

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 12

Example: Graphite vs Carbon Composit

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 13

BNL E951: 24 GeV, 3 x 1012 protons/pulse

BNL E951 Target Experiment 24 GeV 3.0 e12 proton pulse on Carbon-Carbon and ATJ graphite targets

Recorded strain induced by proton pulse

-8

-6

-4

-2

0

2

4

6

8

10

0 0.0002 0.0004 0.0006 0.0008 0.001

Time (sec)

Mic

ros

tra

in

C-C composite

ATJ Graphite

Strain Gauge Measurements

ATJ Graphite

Carbon-Carbon

Composite

Stress =Y αT U / CV

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 14

Carbon-Carbon CompositeAverage Proton Fluence

( 1020 protons/cm2)

0.76

{ 0.52 and 0.36

0.13

none

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 15

Super-Invar CTE measurements

Peak Proton fluence1.3 x 1020 protons/cm2

BNL BLIP

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 16

Recovery of low αT

Carbon-Carbon anneals at ~3000C Super-Invar anneals at ~6000C

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 17

The International Design Study Baseline

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 18

The IDS Neutrino Factory Baseline

Mean beam power 4 MWPulse repetition rate 50 HzProton kinetic energy 5-10-15 GeVBunch duration at target 1-3 ns rms

Number of bunches per pulse 1-3Separated bunch extraction delay 17 µsPulse duration: ≤ 40 µs

The IDS Proton Driver Baseline Parameters

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 19

The Neutrino Factory Bunch Structure

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 20

Driver Beam Bunch Requirement

Proton beam bunch length requirements due to rf incorporated in the downstream phase rotation and transverse cooling sections.

Bunch length = 2± 1 ns

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 21

MARS15 Study of the Hg Jet Target Geometry

Previous results: Radius 5mm, θbeam =67mrad Θcrossing = 33mrad

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 22

Optimized Meson Production

Production of soft pions is most efficient for a Hg target at Ep ~ 6-8 GeV,

Comparison of low-energy result with HARP data ongoing

RadiusPrevious baseline 0.5cm

Beam AnglePrevious baseline 67 mrad

X. Ding, UCLA

Beam/Jet Crossing AnglePrevious baseline 33mrad

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 23

() /Ebeam, integrated over the measured phase space (different for the two groups).

HARP (p + Pb -> +- X) HARP-CDP (p + Ta ->

+- X)

peaks in range 4~7 GeV => no dramatic low E drop-off

Jim Strait – NUFACT09

23J. Strait - FermilabNuFact ‘09

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 24

HARP Cross-Sections x NF Capture Acceptance

HARP (p + Pb -> +- X) HARP-CDP (p + Ta -> +- X)

24NuFact ‘09 J. Strait - Fermilab

HARP pion production cross-sections, weighted by the acceptance of the front-end channel, and normalized to equal incident beam power, are relatively independent of beam energy.

Harold G. KirkBrookhaven National Laboratory

Multiple Proton Beam Entry Points

p0

p8

p4p12

jet

Proton beam entry points upstream of jet/beam crossing

Proton BeamEntry points

Entry pointsare asymmetricdue to the beam tilt in a strong magnetic field

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 26

Trajectory of the Proton Beam

-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

z=-37.5cm

p14, z=-75cm

p11, z=-75cm

p8, z=-75cm

p5, z=-75cm

p2, z=-75cm

Vary z from -75cm to -37.5cm in steps of 2.5cm

Y(p

roto

n)-Y

(jet

), c

m

X(proton)-X(jet), cm

Selected proton beam transverse trajectories relative to the Hg Jet.

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 27

Multiple Entry Entries

p11

p4

A 10% swingin meson productionefficiency

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 28

Influence of β* of the Proton Beam

β* = 10cm β* = 300cm

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 29

Meson Production vs β*

Meson Production loss ≤ 1% for β* ≥ 30cm

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 30

The MERIT Experiment at CERN

1234

Syringe PumpSecondaryContainment

Jet Chamber

ProtonBeam

Solenoid

BeamWindow

Hg Jet

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 31

Installed in the CERN TT2a Line

Before Mating

After Mating and Tilting

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 32

Optical Diagnostics

1 cm

Viewport 2 100μs/frasVelocity Analysis

Viewport 3 500μs/frasDisruption Analysis

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 33

Stabilization of Jet by High Magnet Field

Jet velocities: 15 m/s

Substantial surface perturbations mitigated by high-magnetic field.

0T 5 T 10 T 15 T

MHD simulations (W. Bo, SUNYSB):

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 34

Disruption Analysis

Disruption lengths reduced with higher magnetic fields

Disruption thresholds increased with higher magnetic fields

14 GeV 24 GeV

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 35

10TP, 10T

20TP, 10Tt=0 t=0.175 ms t=0.375 ms

V = 54 m/s

t=0.075 ms

t=0 t=0.175 ms t=0.375 mst=0.050 ms

V = 65 m/s

Velocity of Splash: Measurements at 24GeV

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 36

Filament Velocities

0 25 50 75 100 125 1500

20

40

60

80

100

120

140

160

180

Peak energy deposition (J/g)

Max

. Fila

men

t ve

loci

ty (

m/s

)

B=5T,24GeV B=10T,24GeV B=15T,24GeV B=5T,14GeV B=10T,14GeV Fit,B=0T Fit,B=5T Fit,B=10T Fit,B=15T Fit,B=20T Fit,B=25T

Ejection velocities are suppressed by magnetic field

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 37

Pump-Probe Studies

Test pion production by trailing bunches after disruption of the mercury jet due to earlier bunches

At 14 GeV, the CERN PS can extract several bunches during one turn (pump), and then the remaining bunches at a later time (probe).

Pion production was monitored for both target-in and target-out events by a set of diamond diode detectors.

PUMP: 12 bunches, 12 1012 protons

PROBE: 4 bunches, 41012 protons

Diamond Detectors

Proton Beam

Hg Jet Target

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 38

Pump-Probe Data Analysis

No loss of pion production for bunch delays of 40 and 350 s,

A 5% loss (2.5- effect) of pion production for bunches delayed by 700 s.

Production Efficiency: Normalized Probe / Normalized Pump

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 39

Study with 4 Tp + 4 Tp at 14 GeV, 10 T

Single-turn extraction 0 delay, 8 Tp

4-Tp probe extracted on subsequent turn 3.2 μs delay

4-Tp probe extracted after 2nd full turn 5.8 μs Delay

Threshold of disruption is > 4 Tp at 14 Gev, 10 T.

Target supports a 14-GeV, 4-Tp beam at 172 kHz rep rate without disruption.

PUMP: 8 bunches, 4 1012 protons

PROBE: 8 bunches, 41012 protons

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 40

Key MERIT Results

Jet surface instabilities reduced by high-magnetic fields Hg jet disruption mitigated by magnetic field

20 m/s operations allows for up to 70Hz operations 115kJ pulse containment demonstrated

8 MW capability demonstrated Hg ejection velocities reduced by magnetic field Pion production remains stable up to 350μs after previous beam impact 170kHz operations possible for sub-disruption threshold beam intensities

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 41

The MERIT Bottom Line

The Neutrino Factory/Muon Collider target concept has been validated for 4MW, 50Hz operations.

BUT

We must now develop a target system which will support 4MW operations

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 42

MERIT and the IDS Baseline

Mean beam power 4 MWPulse repetition rate 50 HzProton kinetic energy 5-10-15 GeVBunch duration at target 1-3 ns rms

Number of bunches per pulse 1-3Separated bunch extraction delay 17 µsPulse duration: ≤ 40 µs

NERIT

OK OK

6 µs≤ 350 µs

The IDS Proton Driver Baseline Parameters

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 43

IDS-NF Target Studies

Follow-up: Engineering study of a CW mercury loop + 20-T capture magnet

Splash mitigation in the mercury beam dump. Possible drain of mercury out upstream end of

magnets. Downstream beam window. Water-cooled tungsten-carbide shield of

superconducting magnets. HTS fabrication of the superconducting magnets. Improved nozzle for delivery of Hg jet

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 44

Summary MERIT has successfully demonstrated the Neutrino Factory/Muon Collider target conceptTarget studies are continuing within IDS-NF framework The infrastructure for a 4MW target system needs to be designed/engineered

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 45

Backup Slides

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 46

The MERIT Experiment at CERN

MERcury Intense Target

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 47

Profile of the Experiment

14 and 24 GeV proton beam Up to 30 x 1012 protons (TP) per 2.5s spill 1cm diameter Hg Jet Hg Jet/proton beam off solenoid axis

Hg Jet 33 mrad to solenoid axis Proton beam 67 mrad to solenoid axis

Test 50 Hz operations 20 m/s Hg Jet

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 48

The Jet/Beam Dump Interaction

T. Davonne, RAL

Harold G. Kirk

AHIPA, FNAL Oct. 19-21, 2009 49

Shielding the Superconducting Coils

MARS DoseRate calculations

High-Power Targets H.G. Kirk

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