Transcript JPARC Horn 2 assembly

Conceptual design of
JPARC Horn 2 assembly
L. Bartoszek
Bartoszek Engineering/CU
5/5/04
Assembly Scenario
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The pictures in this presentation
show an assembly scheme for Horn 2
which parallels that of the MiniBooNE
horn with a significant exception
• The last assembly step requires welding
instead of bolting and is caused by the
thin end cap region
Step 1: Lower IC into OC
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The fixture for welding the IC is not
shown
I did not spend time on figuring out
the segments of the IC or the
welding process
This scenario starts after all but the
last weld is done
Step 2: Make one end of horn
water tight
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I assume a bolted connection at the
end of the horn opposite the strip
line, but it could be welded.
Water and current-carrying seals are
not shown here
Step 3: Rotate horn 180 degrees
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MiniBooNE rotated the horn to make
measurements that allowed us to cut
the last piece so that when the horn
was bolted together the IC was in a
state of zero stress—no tension or
compression prior to pulsing
Rotating also allows the final
operations to be done from on top
instead of below—easier and safer
Fixtures needed to hold inner
conductor to outer prior to
rotating the horn on the
rotating fixture
Photos show the MiniBooNE
fixtures
Water ports make handy
places to mount fixturing
between the inner and outer
conductors
Step 4: Add ceramic ring
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The ceramic ring isolates the inner
and outer conductors where the
stripline connects to the horn
MiniBooNE made a lifting fixture for
the ring because it was too heavy for
people on ladders
• Also put water seals in at this end (not
shown)
MiniBooNE ceramic ring
lifting fixture
Step 5: Assemble studs
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Ceramic tubes isolate the fasteners
that clamp the inner and outer
conductors to the ceramic ring
A ceramic pin was used in MiniBooNE
to cause angular alignment between
pieces. May not need it here
Step 6: Assemble flange
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This flange must be welded to the
inner conductor to allow current from
the stripline to make a complete
circuit
MiniBooNE’s upstream flange could
be bolted because it was thick
• This flange is too thin to bolt
The thickness of the upstream
end of the MiniBooNE horn
allowed a bolted connection
between the flange and the inner
conductor
Step 7: Compress water seals
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More ceramics are used as insulating
washers to compress the flange to
the outer conductor, squeezing the
water seals and the ceramic ring
All ceramics are used in compression
where they have significant strength
• I cannot recommend putting ceramics in
tension
Step 8: Final weld connection
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Once the water seals on both sides
of the ceramic ring are tight the last
weld that connects the flange to the
inner conductor can be done
The weld prep on the flange can only
be cut after the final length of the
inner conductor is known (after weld
shrinkage)
Step 9: Corona ball assembly
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The threaded rods have sharp edges
that could cause breakdown with the
high voltage of the stripline
• The solid model does not show these
edges on the threads
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Corona balls hide the sharp edges
and prevent corona discharge
Ready for attachment to striplines
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At this point the horn can be
mounted to its support module and
fitted out with water nozzles,
stripline connections and everything
else