FERMILAB HIGH POWER

TARGET R&D PROGRAM

NBI 2012 P. Hurh (FNAL) Nov. 8, 2012

Overview

Fermilab High Power Target Facility Needs

High Power Target Challenges

High Power Target R&D Activities

Future Plans

Current Target Facilities

Fermilab Accelerator Division operates 3 target

facilities:

P-bar Source (off) – 70 kW proton beam on inconel

(nickel alloy) target with Be cover (110 kW/mm2)

NuMI/MINOS – 400 kW proton beam on graphite

(carbon) target (14 kW/mm2)

Soon to be 700 kW beam for NOvA

MiniBooNE – 32 kW proton beam on beryllium target

(1 kW/mm2)

Note: Values in red refer to total beam power divided by nominal 3 sigma spot size,

not energy deposition in target and not peak values

Near to Mid-Term Future Target

Facilities (<10 years)

Currently have resources working on:

ANU/NOvA - 700 kW p beam on graphite (15 kW/mm2)

LBNE-1- 700 kW p beam on graphite (Be?) (15 kW/mm2)

Mu2e – 8 kW - 8 GeV p beam on W (0.4 kW/mm2)

G-2 – 27 kW - 8 GeV proton beam on inconel (??)

Just starting to consider:

ORKA – 74 kW – 95 GeV proton beam on platinum (??)

NuSTORM – 100 kW- 60 GeV proton beam on Ta or W

(??)

Note: Values in red refer to total beam power divided by nominal 3 sigma spot size,

not energy deposition in target and not peak values

Note: High Z targets will have much higher energy deposition per proton

Mid-Term to Far-term (>10 years):

Project X Reference Design

Project X Staging Layout

Fermilab HPT R&D Program

Approach:

Large number of facilities contemplated and budgetary

uncertainties

Address HPT R&D at fundamental level not necessarily

specific to any single facility

Build HPT technology and infrastructure as a “core

competency” at Fermilab (such as SRF)

Be poised to embark on informed design of the next

large machine (Nu Factory/Muon Collider)

HPT Challenges

Thermal Shock (Stress Waves)

Heat removal

Radiation Damage

Radiation Accelerated Corrosion

Spatial Constraints and Shielding

Residual Radiation

Manufacturing techniques

Physics Optimization Not just targets, but entire target systems (beam windows, collection

optics, absorber, decay pipe, etc.)

Thermal Shock

Fast expansion of material surrounded by cooler material creates a sudden local area of compressive stress

Stress waves (not shock waves at these load rates) move through the target

Plastic deformation and/or cracking can occur

Ta-rod after irradiation with 6E18 protons in 2.4 s

pulses of 3E13 at ISOLDE (photo courtesy of J. Lettry)

Simulation of stress wave propagation in Li lens

(pbar source, Fermilab)

Heat Removal

About 7.5 kW total energy deposited (NOvA – 700 kW primary beam target)

Easy to remove with water

Tritium production

Hydrogen gas production

Thermal shock in water (Water Hammer)

BUT:

Radiation Damage

Tungsten cylinders irradiated with 800 MeV protons and compressed to 20% strain at RT. A) Before irradiation

B) After 3.2 dpa

C) After 14.9 dpa

D) After 23.3 dpa

Data exists for neutron irradiation, less for proton irradiation

Gas production much higher for high energy particle irradiation S. A. Malloy, et al., Journal of Nuclear Material,

2005. (LANSCE irradiations)

Radiation Accelerated Corrosion

Al 6061 samples

displayed significant

localized corrosion

after 3,600 Mrad

exposure

NuMI target chase air handling condensate with pH of 2

NuMI decay pipe window concerns

R.L. Sindelar, et al., Materials

Characterization 43:147-157

(1999).

Radiation Accelerated Corrosion

MiniBooNE 25 m absorber HS steel failure

(hydrogen embrittlement from accelerated corrosion).

Fermilab HPT R&D Activities

Radiation Damage Research

Found to be most cross-cutting HPT challenge (PASI 2012)

Opportunity for leveraging fission/fusion knowledge base and materials science expertise

RaDIATE Collaboration

Thermal Shock Research

Verification of simulation tools (elastic & plastic)

Strain rate dependencies

Failure criteria (when is a target really failed, Hartsell Talk)

Many other ongoing efforts (autopsies, cooling studies, novel target concepts (pebble bed, Be spheres)

RaDIATE Collaboration

Radiation Damage In Accelerator Target Environments

From the MOU:

The Participants intend for the research program to include those

activities which develop a better understanding of radiation

damage mechanisms and the associated thermal and mechanical

properties response for materials of interest to future high

power proton beam target facilities.

Enlisting the aid of fission and fusion power materials

experts as well as current researchers in the accelerator

domain

Initial Collaborators: FNAL, BNL, STFC, PNNL, Oxford

RaDIATE Collaboration Capabilities

Each Institution brings unique and overlapping expertise and capabilities

Fermilab: Operating experience with Target Facilities and Target design expertise

BNL: Extensive Materials Science expertise and BLIP irradiation station (current site for HE proton radiation damage research under Nick Simos)

STFC: Operating experience with ISIS, Target design experience, Materials Science expertise and more

PNNL: Extensive radiation damage (nuclear reactor) experience, hot lab capability with advanced research instruments (SEM, TEM, Atom probe, tensile, fatigue, etc…)

Oxford: Extensive radiation damage (nuclear reactor) experience, advanced research instruments (SEM, TEM, Atom probe, tensile, fatigue, etc…), advanced techniques for materials evaluation (micro-mechanics)

Why use micro-mechanical testing?

Useful where only small samples are available Cost

Processing

Need for a sample design that can be machined in surface of bulk samples

Suitable for measuring individual microstructural features

Samples that can be manufactured quickly and reproducibly

1um

3m 10m

4m

3m

3m

D.E.J Armstrong 2011

19

Microcantilever Manufacture

10m

07/11/2012 D.E.J Armstrong 2011

2m

Current State of the Art

07/11/2012 D.E.J Armstrong 2011

General boundary

S3 - twin

Testing of micro-cantilevers

07/11/2012 D.E.J Armstrong 2011

Fracture at 600oC

1µm

RaDIATE Activities

Stage 1: Exploratory and Development (6 month)

Recruit materials science post-doc based at Oxford

Develop experimental research program

Consider graphite, beryllium, tungsten, and C-C composite initially

Survey of existing, irradiated sample material

Continue radiation damage studies at BLIP (Simos talk)

Just started

Stage 2: Experimental Stage (1-2 years)

Irradiate new materials or use existing targets/windows?

Intense PIE (perhaps made easier by micro-mechanics)

RaDIATE Activities (con’t)

Stage 3: Report writing (1 year)

Publications

Set direction for future work

Disseminate findings to HPT community

Looking for additional collaborators

Contact me if interested

Thermal Shock R&D

Elastic response simulations have been verified

Plastic and failure, not so much Some work at GSI by Lettry with U beam

Classic definition of failure (yield) perhaps too conservative

Failure of target is generally if it holds together for the next pulse!

Evidence that materials can take much more than we have thought in the past (beam windows especially)

High strain rate

Plastic deformation “pre-loading”

Ductility at higher temperatures (annealing of rad damage as well!)

Possible testing at Hi-Rad Mat

Talk by Brian

Hartsell on

initial studies

Future HPT R&D Program Plans

Continue leading RaDIATE

Continue Thermal Shock R&D

Continue other studies as resources allow

Build HPT expertise as a “core competency” rather than specific to a particular project

Coordinate R&D activities globally

In times of shrinking budgets, must be efficient

By pooling resources can attack larger problems to gain fundamental understanding, applicable to many future target facilities

But compromises will have to be made and accepted when doing general research rather than specific research