Booster RF Cavities
- Booster accelerates 400 MeV protons from the linac up to 8 GeV for
injection to MI, MiniBooNE
- Down time in the Booster often results from the need to perform regular
maintenance to RF cavities and power supplies
- Currently the RF cavities are the smallest aperture in the machine
-> cavities get activated
- Further, Booster can cycle at 15Hz, but currently, to avoid above problem,
only run at half that -> less protons!
Current RF Cavities:
- 18 RF cavities operate in the Booster at a frequency of
53MHz, each producing ~55kV
- The beam pipe aperture is 2.25 inches
- Cavity frequency controlled by 3 ferrite loaded variable inductors,
"tuners"
- 150 kW power amplifier mounted on top of the cavity
RF Upgrade:
- Proposal is to build larger aperture cavities increasing the beam pipe
from 2.25 to 5 inches
- This will reduce beam loss and therefore activation in the cavities,
allowing for regular maintenance during high duty factor operation
- Also requires minor modifications to the old designs and the fabrication
of new parts
A mechanical prototype has been constructed using a damaged Booster RF cavitiy
and tested using existing tuners. Preliminary tests were hopeful, although
there is concern that the existing tuners will not be suitable in their current
configurations.
The next step is to build two working prototypes that can be installed into
the Booster during the summer shutdown. The nominal schedule is as follows
(from last RF Upgrade meeting):
Fabrication of cavity parts and tooling:
mid-Feb to
mid-April
Assembly of cavities:
mid-April to end
of June
Electrical measurements:
July
Installation:
1st week of Sept (golden
opportunity!)
There was a call at the last meeting for this scedule, particularly the assembly
at this stage, to be further broken down.
University involvement will be the materials purchase and fabrication
of the cavity parts and tooling AT NO COST TO FERMILAB! Bill Sands (engineer
from Princeton) received 7 drawings yesterday which were to be distributed
to relevant people at interested MINOS and MiniBooNE institutions. A further
3 will also be distributed in ~week, as well as drawings for tooling items
required for the assembly of the cavities.
A number of other parts also need to be fabricated however they are to be
fashioned from old radioctive Booster RF cavities and so will be done at
Fermilab.
This is the first step towards undertaking a larger project to build 20 of
the large aperture cavities where the universities are heavily involved at
each step of the construction and installation. For this reason, it is important
for the universities to get involved at this stage of the project.
A description of the large aperture RF cavitiy can be found in the Proton
Driver Study: http://www-bd.fnal.gov/pdriver/reports.html
Chapter 5, RF Systems.