Dear Dr. Borland,
I want to do simulation study for coupled bunch instability in a storage ring in which harmonic number is 1536 and I want to fill all 1536 bunches with 10,000 electrons in each bunches using particle ID and tracked for 5000 turns. Is the process of making lattice file is the same as is given example of 48 equally spaced bunches out of 1296 RF buckets in APS using PELEGANT code? Is there any restrictions or limitations on the number of bunches or number of electrons in one bunch to be filled? How we decide the minimum number of electrons in a bunch to be taken for simulation study?
with regards, Pradeep Kumar
Study on coupled bunch Instability in ultra-low emittance ring
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michael_borland
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Re: Study on coupled bunch Instability in ultra-low emittance ring
Pradeep,
The procedure should be very similar to the 48-bunch example, just changing 48 to 1536 in various places. There is no meaningful limit on the number of bunches, beyond memory limitations related to the total number of particles.
The number of particles need not be that large if you are only interested in coupled bunch instabilities; e.g.,1000 should do fine. If you also include the short-range wake, then 10k particles is a good choice if you are below the microwave instability threshold, whereas you should have 30-100 k if you are above the threshold. These are general guides. You should vary the number to ensure that the results are insensitive to the number of simulation particles.
An alternative for computing the CBI growth rates is the program clinchor, which is available on our web site. It uses a point-particle approximation and supports arbitrary bunch patterns. If you have no other collective phenomenon to worry about and no harmonic cavities, it should give the same results as tracking with much less computation. More information is available from the manual.
--Michael
The procedure should be very similar to the 48-bunch example, just changing 48 to 1536 in various places. There is no meaningful limit on the number of bunches, beyond memory limitations related to the total number of particles.
The number of particles need not be that large if you are only interested in coupled bunch instabilities; e.g.,1000 should do fine. If you also include the short-range wake, then 10k particles is a good choice if you are below the microwave instability threshold, whereas you should have 30-100 k if you are above the threshold. These are general guides. You should vary the number to ensure that the results are insensitive to the number of simulation particles.
An alternative for computing the CBI growth rates is the program clinchor, which is available on our web site. It uses a point-particle approximation and supports arbitrary bunch patterns. If you have no other collective phenomenon to worry about and no harmonic cavities, it should give the same results as tracking with much less computation. More information is available from the manual.
--Michael