NBI 14-19 March 2002
The MiniBooNE Horn
Ioanis Kourbanis
For
The MiniBooNE Collaboration
NBI 14-19 March 2002
Outline
List of people Horn characteristics Horn Power Supply Horn Striplines Highlights of Horn Construction and Assembly Horn Testing Horn Changeover Future Plans
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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 SCR’s
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
DESIGN OPERATION
Pulse Amplitude(KA)
250 170
Rep. Rate(Hz)
7.5 5.0
Circuit Inductance(microH)
1.78 1.33
Operating Voltage(kV)
9.5 5.4
Average Power(kW)
62 19
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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.