IPNS Third RF Cavity Status Report

A U.S. Department of EnergyOffice of Science LaboratoryOperated by The University of Chicago

Argonne National Laboratory

Office of ScienceU.S. Department of Energy

IPNS Third RF Cavity Status ReportG.E. McMichaelAccelerator Facilities Manager

Presentation at the Ninth SHRF/LOIA Collaboration Meeting

June 14, 2004

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Pioneering Science andTechnology

Office of Science U.S. Department

of Energy

IPNS ACCELERATOR OVERVIEW

• Accelerator delivers a short (70 ns) intense

(3 x 1012 protons/pulse) pulse of 450 MeV protons to the depleted-uranium target 30 times per second

• Each proton produces about 15 neutrons

• IPNS is a user facility. Sole purpose of the accelerator is to produce neutrons (99% for the neutron-scattering instruments in Bldg. 375, remainder for an “exotic-beam” source for ATLAS)

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of Energy

IPNS ACCELERATOR FACILITY• Three accelerators in series

- 750 keV Preaccelerator- 50 MeV Linac- 450 MeV Rapid Cycling

Synchrotron (RCS)• Ancillary Systems

- RF (Variable Frequency Beam Feedback controlled)

- Magnets and power supplies (Pulsed & DC)

- Control, diagnostics and data acquisition

- Vacuum- Safety (Personnel & Equipment)

• Buildings and Utilities - AC Power- Water Systems- Air Conditioning

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of Energy

HISTORY

• Preaccelerator and linac entered service in 1961 as injector to the 12.5 GeV ZGS (Zero Gradient Synchrotron) high-energy physics accelerator

• RCS developed in mid 1970's as a proposed booster for ZGS. Excess beam would have been available for a spallation neutron source

• ZGS was shut down in 1979. RCS initially (1977-1980) provided beam into the ZING experimental target. First beam to IPNS target was in 1981

• Eight-billionth pulse 16 April, 2004

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of Energy

ION SOURCE & PREACCELERATOR

• Magnetron-type H- ion source, cesium getter

• Extraction at 20 keV, magnet to separate electrons

• Cockcroft-Walton generator, 750 Kv

• Output H- beam, 30 mA peak, 70 µs pulses, 30 Hz

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of Energy

LINAC

• Alvarez-type “drift-tube linac”

• Copper-clad steel tank, 33.5 m long, 0.93 m diameter

• 124 drift tubes, each with a dc quadrupole magnet

• 200 MHz rf transmitter, triode amplifier tube, 3.5 MW

• Output H- beam 50 MeV, 10 mA peak, 70 µs pulses, 30 Hz

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of Energy

• 8 Dipole horizontal bending magnets

• 6 Dipole vertical steering magnets

• 16 Quadrupole focusing magnets

• 12 Wire scanners, 6 Beam position monitors

• Transports H- beam ≈ 40 m from linac to RCS

50 MEV TRANSPORTATION LINE

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of Energy

RAPID CYCLING SYNCHROTRON “ RCS”

• 43 m circumference strong-focusing, combined-function synchrotron

• 6-sector machine, magnet structure D00FDF0

• Betatron tune correction provided by two pairs of sextupole magnets

• Multi-turn injection ( 130 turns, “3 mile string”)

• Single-turn extraction by two ferrite-loaded kicker magnets and two septum magnets

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of Energy

RAPID CYCLING SYNCHROTRON “ RCS”

• Ring magnets are part of a biased 30 Hz resonant circuit. Generate a magnetic field that varies from 0.28 to 1 Tesla during the accelerating cycle

• Thin carbon foil strips off the two electrons

• Two rf cavities to bunch and accelerate the proton beam

• Third rf cavity will be installed in L6 section

• Output proton beam 450 MeV, 70-80 ns pulse, 30 Hz, 3 x 1012 protons/pulse

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of Energy

PTS BEAMLINE

• 4 Dipole horizontal bending

magnets

• 2 Dipole vertical steering magnets

• 15 Quadrupole focusing magnets

• 6 Segmented secondary emission

monitors, 1 Segmented wire ion

chamber

• Transports H- beam ≈ 45 m from

RCS to neutron-generating target

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of Energy

ACCELERATOR OPERATIONS

OPERATING PERIODS

• Typically two to four weeks on and one to two weeks off

• Six-hours reserved each Tuesday for machine research and

moderator regeneration

• Two longer shutdowns (Christmas and summer) for installations

and larger maintenance jobs

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of Energy

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of Energy

THIRD RF STATION

• Cavity almost identical to two existing

• Redesigned rf amplifier systems:

- Pre-driven and final use new tubes

- Driver is an updated version of existing systems

- New low-level system

• Provide second-harmonic rf for capture and initial acceleration

• Provide additional fundamental at mid-cycle

• Can function as on-line spare for existing fundamental

systems

• Installation to start in 6 months

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of Energy

2nd – HARMONIC RF

• Propose to enhance 3rd rf system to operate at 2nd harmonic throughout the acceleration cycle

• Principal addition will be a new cavity with different ferrite

• Funding and schedule uncertain

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SUMMARY

• IPNS continues to have a moving 10-year window – to ensure

reliable operation for the next 10 years

• Recent budget problems have slowed the upgrade/assurance

program.

• Our interest in the collaboration remains strong - Shaoheng

Wang will be joining our program

IPNS Third RF Cavity Status Report

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