The MiniBooNE Horn

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The MiniBooNE Horn

• Ioanis Kourbanis
• For
• The MiniBooNE Collaboration

2
Outline

• List of people
• Horn characteristics
• Horn Power Supply
• Horn Striplines
• Highlights of Horn Construction and Assembly
• Horn Testing
• Horn Changeover
• Future Plans

3
List of People

• C. Anderson
• L. Bartotzek (Bartoszek Engineering)
• L. Bartelson
• L. Bugel
• C. Jensen
• H. Le
• B. Markel (Markel Associates)
• J. Misek
• F. Nezrick
• H. Pfeffer
• R. Reilly
• D. Snee
• M. Sorel
• E. Zimmerman

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Horn Characteristics

• We are using one horn with a narrow neck and a
  conical inner conductor (BNL Design) designed to
  run at a current of 170 KA.
• The horn is made out of Al alloy 6061-T6 and is
  excited by a 143 ?sec current pulse.
• Keep the voltage at the PS below 10 KV (use solid
  state SCRs instead of thyristors)
• Reduce the current pulse width as much as
  possible to avoid excessive heating of the horn .
• Keep the voltage at the horn as low as possible
  (small inductance).
• The horn will operate at an average rep rate of 5
  Hz. Total average power deposited in the horn is
  2.4 KW.

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3-D Model of the Horn
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Horn Power Supply

• The Power Supply consists of a Capacitor bank
  (1,344 ?F) discharged through an inductive load
  by an SCR switch. The system has a separate
  circuit for energy recovery.
• The circuit is divided into 16 parallel
  capacitors, each with its own SCR switch.

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Horn PS Parameters
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Power Supply Schematic
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Power Supply View (Front)
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Power Supply View (Back)
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Horn Stripline

• Balanced design (odd number of conductors) to
  minimize forces.
• The conductor spacing is 1 inch. Fluted alumina
  insulators with a 2 inch creepage length were
  used to separate the conductors.
• The test stripline piece, along with a clamped
  joint, were corona tested.
• The inductance of the final stripline was
  measured to be 18.5 nH/m.

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View of the Long Stripline Section
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View of a Stripline Joint
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View of the Small Stripline Section
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Construction and Assembly Highlights

• Forged Outer Conductor
• The water sprayers were vibration isolated from
  the Horn Outer Conductor.
• Solid connections from the striplines to the
  Horn.
• The Horn Inner Conductor was welded at Fermilab
  using a programmable TIG welding machine.

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Outer Conductor after Forging
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Outer Conductor after Machining
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Outer Conductor after Welding
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Water Manifolds
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Water Truss
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Water Truss and Water Manifolds
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Water Truss Bellows Detail
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Water Connection Detail
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Outer Conductor with Water Truss
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Water Drain Connection
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Water Nozzle Detail
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Twist Transitions
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Inner Conductor Before Welding
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Hand Scraping before Welding
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Welding Sample
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Large Weld
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Small Diameter Weld
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Inspecting the Small Diameter Weld
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Radiography of Weld
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Radiography of Large Weld
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Moving the Inner Conductor from The Welding
Machine
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Inserting the Inner into the Outer Conductor
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Horn Testing

• The horn was pulsed for the first time on
  07/27/01.
• The horn test was completed on 02/12/02 after
  completing 11M pulses at full current.
• We completed horn magnetic field measurements.
• Completed a series of vibration measurements.
• Things we were monitoring
• Total current
• Current in the four striplines feeding the horn
• Total voltage
• Cooling water supply and return temperatures
• Horn temperatures

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Overview of MI-8 Test Area
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Horn module overview
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Stripline Configuration at the TSB
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Current and Voltage Profiles
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Horn Magnetic Field Measurement
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Horn Temperature Profiles with Different Sprayer
Configurations
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Correlation between Horn and Water Return
Temperatures
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Horn Vibration Spectrum
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Horn Axial Displacement vs. Time
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Horn Changeover

• The horn module is expected to be highly
  radioactive (30 Rad/hr at 2 ft).
• In order to reduce the Radiation Exposure to
  under 100 mR/hr at 1 ft, the shielding
  requirement is 5 of steel on all sides.
• Because of the crane lifting capacity, two
  separate coffins (an inner and an outer ) will be
  used.
• The inner coffin has 1.5 thick walls except
  from the top cover and the front door (5 thick).
• The outer coffin has 3.5 thick walls and is open
  at the top and the front.

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Horn Changeover (2)

• The radioactive horn module will be stored inside
  the two coffins in the Target Service Building in
  the old Proton Line.
• Four coffins (two inner and two outer coffins)
  will be needed for a changeover.
• A detailed procedure outlining all the steps for
  a changeover has been written and reviewed.
• Total estimated time for a changeover is 2 weeks.

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Inner Coffin
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Outer Coffin
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Initial Configuration
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Inner and Outer Coffins
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Open Inner Coffin Door
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Position the Coffins next to the Horn Module
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Pull the Horn Module in the Coffin
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Close Inner Coffin Door
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Future Plans

• We have started disassembling the Power Supply
  and the Striplines.
• The horn modules will be stored in the inner
  coffin.
• Plan to install the horn in the target pile on
  May 7.
• We estimate to be ready for a horn changeover
  test on May 15.
• We should be ready for beam on June 15.
• We have started ordering the large pieces for a
  spare horn.