The RAL Front End Test StandDavid Findlay for Alan LetchfordAccelerator Division, ISIS DepartmentRutherford Appleton Laboratory

HIPPI-05, Cosener’s House, Abingdon, 28–30 September 2005

22

RAL Front End Test Stand (FETS)Part of CCLRC’s generic R&D programme on high power proton acceleratorsSpecifically, demonstration of some key technologies for the front ends of

Spallation neutron sourcesNeutrino factoriesWaste transmutersTritium productionEnergy amplifier

33

FETS is a collaborative effort amongstCCLRC RAL ISISCCLRC ASTeC Intense Beams GroupDept. Physics, Imperial College, LondonDept. Physics, University of Warwick

Promotion of accelerator science in UK universities

44

FETS collaboratorsJohn Back, Giulia Bellodi,Mike Clarke-Gayther, Dan Faircloth, Graham Gosling, Stephen Jolly,Ajit Kurup, Alan Letchford,Eddie McCarron, Ben Pine,Dan Ciprian Plostinar, Jürgen Pozimski, Peter Savage, Mark Whitehead,Trevor Wood

55

FETS fundingCCLRC, through ASTeC

ISIS and ASTeC staff + hardwarePPARC, through ASTeC

UK university staffCCLRC, through Infrastructure Fund

Reconfiguration of test stand areaEU, through HIPPI programme

66

RFQ

Chopper

FETS main components:High brightness H— ion sourceMagnetic LEBTHigh current, high duty factor RFQVery high speed beam chopperComprehensive diagnostics

RFQ

Chopper

Building R8 — being reconfigured for FETS

FETS builds on experience from ISIS RFQ test stand

1111

FETS specification60 mA H—, 2 ms, 50 pps75 keV 3-solenoid LEBT3 MeV, 324 MHz RFQ2 ns choppingComprehensive diagnosticsTest stand in practice

1212

H— surface Penning ion source35 mA, 200 µs (ISIS) 60 – 70 mA, 1 – 2 msIncrease largely achieved

Separate Penning fieldThermal modellingElectromagnetic modellingExtensive experimental work on dedicated ion source development rig

-80

-60

-40

-20

0

20

40

60

80

0 500 1000 1500 2000Time (us)

Beam Current (mA)Discharge Current (A)Extract Volts (kV)

Good extraction over 1.75 ms arc at 50 pps

1515

3-solenoid magnetic LEBTDesign proceeding well

Beam chopper[Other talks]

1616

RFQ — 3 MeV, 324 MHzReady availability of Toshiba E3740A 3 MW pulsed klystron (J-PARC)Electromagnetic DTL quadrupoles

1717

RFQ beam dynamics at 324 MHz encouraging

3 MeV, 4 metre design95% transmission, 80 kV electrode voltage

Low voltage design 4-rod type possible4-rod and 4-vane designs being investigated

4-rod RFQ has at least one operational advantage

2020

DiagnosticsFull suite of diagnostics to maximise the experimental capabilities

Beam currentsEmittancesEnergy spectra (magnetic + gas scattering spectrometers)Non-destructive laser/opticalResidual gas ion spectroscopy

2121

Possible beam halo monitor?Activate scandium annulus?45Sc(p,n)45TiEthresh 2.8 MeV, 45Ti t½ 3 hours, 85% β+ decay

Low background2.5 mA mean, 10—5 halo, 100 seconds → 30 BqSc melts

1540°C

2222

Radiation shielding60 mA, 2 ms, 50 pps, 3 MeV into copper

2 – 3 × 1010 neutrons/second ~100 mSv/hour at 1 metre

Say lose 3% ~1 mSv/hour at 2 metres~1 metre concrete ~1 µSv/hour

C (graphite) or Al(-Si alloy) for beam dump?C: 13C(p,n) threshold 3.00 MeV (13C (1.1%)); 10-minute 13N from 12C (p,γ)Al-Si: (p,n) > 5 MeV; no activity from (p,γ)

2323

ConclusionsRAL Front End Test Stand will make an important contribution to HPPA R&DGood progress from RAL/ISIS, ASTeC, Warwick and ImperialBuilds on experience gained with ISIS RFQpre-injector upgradeFirst LEBT beam anticipated for 2006