Transcript RF Power

MICE RF
Daresbury Laboratory Support
Joe Orrett - ASTeC
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Personnel
Daresbury Laboratory RF and Diagnostics
Group will provide three members to
support the MICE Project;
• Andrew Moss – Senior RF engineer
• Joe Orrett – RF engineer
• Peter Corlett – RF engineer
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RF System
•
Discussions between the DL staff, Paul
Drumm and Roy Church on the 6,7th
October agreed the initial thoughts on
development of the MICE RF test stand
•
The brief is to rebuild one 2MW
amplifier to test the feasibility of the
system to power the MICE RF system
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Master Oscillator
Controls etc
Los Alamos
HT
Supplies
CERN
300 kW
Amplifier
2 MW
Amplifier
300 kW
Amplifier
300 kW
Amplifier
300 kW
Amplifier
2 MW
Amplifier
2 MW
Amplifier
2 MW
Amplifier
LBNL
HT
Supplies
Daresbury
201 MHz Cavity Module
201 MHz Cavity Module
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5
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DL Support Areas
• Modelling
– Extensive simulation tools
• Refurbishment
– equipment from LBNL, CERN
• Design
– Low level control electronics
• Recommissioning
– Loaned equipment into a test stand
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Modelling
• DL RF and Diagnostic Group has the
capability to model RF systems using
Microwave Studio and HFSS
• Aspects of the proposed RF system can
be simulated and potential problems
identified
– A 2MW test load made from 4 50KW loads is
a prime candidate for this process
– Hybrid power splitters/circulators will also be
modelled
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Modelling example
• 1.3GHz power
combining/splitting cavity
modelled
• Low power test cavity
manufactured at DL
• Simulation and testing agreed
99%
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Courtesy of Emma Wooldridge, ASTeC
Refurbishment
We will be receiving equipment from
various labs which, in most cases has not
been in service for a considerable length
of time. Upon arrival the following actions
will be carried out;
• Inspection, each item will dismantled and
inspected for mechanical and electrical
integrity. Any remedial action required will
be identified.
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Mechanical/electrical refurbishment
• Refurbishment, mechanical items will be
refurbished to an acceptable standard using the
DL Workshop Facilities.
• Modification, it is likely that much of the electrical
equipment will require some modification:– Heater power supplies and controls
– Cathode modulation system
– HT supplies
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Testing
• Testing, if practical, discrete components
will be independently tested before being
assembled into the RF System.
– Coax sections
– Matching devices
– HT supplies
– Low level electronic components
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Design of Low Level RF electronics
• DL mainly works at 500MHz CW
• Many Interesting RF devices could be
tested as part of the MICE program
• Hope to build and collaborate with RAL
experience
– Copy existing designs for time critical
components
– Use test stand to develop new ideas and
solutions
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Recommissioning
• Recommissioning is likely to
be a challenging process!
• Old, out of service equipments
being reassembled in a new
system are bound to cause
problems.
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4616 Circuit
• LBNL sending 4616 test
stand
• Need to find one more
driver for MICE
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Electrical plant room location
• 415V plant room
• Large cooling
supplies under
floor area
• The area to be
cleared
• Make use of
Bund area?
• Overhead crane
• Large access
doors
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MICE equipment
• LBNL circuits should be arriving very soon
• CERN modulator for 2MW circuit,
discussions continue
• 4616 LANL PSU, MOU under construction
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• 2.5MW HT
– A modulator from the CERN test stand has
become available; this will provide 150A at
32KV at 1Hz 200uS. Discussions are in
progress to see if this can be brought to DL
• I think the conclusion is that this will be
useful to the MICE RF & DL will …
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• Heater
– The heater runs at 17V 450 amps, the psu should come with the
equipment, but might need to be refurbished. RAL have a new
design for this. Running the heater to high will result in a
considerable reduction in lifetime for the tube. Back heating of
the tube heater may occur from the RF drive!
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• Ion pumps
– The circuits use 5KV varian Ion pumps, which are used on site at DL
• Safety issues
– At RAL no X Ray problems have been found in running the tubes,
– Tests at DL will need to be carried out by Heath Physics as soon as HT
is applied to the tubes.
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•
Test Load
–
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TH170
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–
–
•
If the TH116 proves an unsuccessful candidate, CERN use TH 170 tubes for a similar power
level, however the input impedance of these tubes is dramatically different and the 170
needs a tuning stub, CERN will be able to help with this.
Anode dissipation of the tubes is 50KW and 10KW for the 116 & 170 respectively.
Conditioning of these tubes could take up to a day. Reduced HT and low drive levels are
needed to slowly bring tube up to full power. Resonance effects can be cured by using
ferrite absorbers in the output cavity and resistor/capacitor networks on the drive
connections.
4616 Drivers
–
–
•
a coaxial 4-way splitter and four 50KW loads: model various arrangements and purchase
commercially available equipment.
Manufactured by Burle industries a test stand for the 4616 will be included in the shipment
from Berkley as well as 3 circuits (a forth will be needed), Burle are supposed to be finding
drawings of the circuits used at Berkley.
The tubes should come with all the systems ready to drive them, heater, grid and HT psu’s,
and input/output matching sections, but extensive refurbishment will be needed.
HT
–
The 18KV psu for the HT is currently at LANL, PD is liaising with John Lyles over an
MOU. The tube is operated with DC HT and pulsing the screen grid, JL has a design using
mosfets to do this. Screen grid psu information is available from Burle.
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• As yet there is no news of the shipment
– Hope to know before end of week
– and hopefully, tomorrow!
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