ECLOUD simulation results to be discussed at today's meeting can be
found here:
http://www.lns.cornell.edu/%7Ecritten/cesrta/ecloud/18jun08/
Plots of density vs time, cloud snapshots, etc are in ecloud_nnn.pdf.
Plots of spatial, velocity and energy distributions of electrons hitting
the wall
are in wall_nnn.pdf
The ECLOUD input files are also in the directory.
Four high-statistics jobs are running:
1) Job 278: Standard L3 conditions as defined by Gerry's spreadsheet
(see Joe's
and Gerry's talks of yesterday, as well as my job 273, also on the
wiki), but with
the bunch current reduced from 4.4 mA to 0.25 mA.
2) Job 285: Standard L3 conditions, but with a bunch pattern of 9x1x10 mA
rather than 1x45x0.25 mA.
3) Job 282: Job 278 conditions, with 10 G solenoid field.
4) Job 284: Job 285 conditions, with 10 G solenoid field.
I will update the plots as the jobs progress.
Some preliminary comments:
1x45 (the jobs are about 1/2 finished)
-----------------------------------------------
1) The equilibrium 1x45 average density in the pipe is 1.2E10 e/m^-3,
i.e. 7E7 e- in the pipe.
The 5-sigma central density is 1e10 e/m^-3, spiking to 3.5e10 following
passage of
the 45th bunch. The equilibrium average density drops to 5e9 e/m^-3 with
10 G
of solenoidal field. The 5-sigma density calculation suffers from
statistics, but
is less than 2E8 e/m^-3 at all times with the solenoid on.
2) Of 78k macroparticles hitting the wall in this 1x45 configuration,
none have a
kinetic energy greater than 35 eV. The same is true of the 112k
macroparticles
which hit the wall with the solenoid on.
9x1 (the jobs are about 1/3 finished)
----------------------------------------------
3) The peak density in the pipe is 1.8E9 e/m^-3, i.e. 1.2E7 e- in the
pipe, dropping
an order of magnitude before the next bunch passage.
The peak 5-sigma central density is 6E9 e/m^-3.
The peak density with 10G of solenoidal field is again 1.8E9 e/m^-3,
apparently unaffected by the field.
The 5-sigma density calculation again suffers from statistics, but
is less than 1E8 e/m^-3 at all times with the solenoid on.
4) Of 4.8k macroparticles hitting the wall in this 9x1 configuration,
none have a
kinetic energy greater than 25 eV. The same is true of the 6.6k
macroparticles
which hit the wall with the solenoid on.
---------------------------------------------
5) The overwhelming majority of the electrons hitting the wall do so near
the source point in each of the calculations, consistent with the
CLOUDLAND results
shown by Joe yesterday.
===============================================================
I have updated the wiki page:
https://wiki.lepp.cornell.edu/ilc/bin/view/Public/CesrTA/ElectronCloud
Gerry, Joe, if you want to send me pdf's from yesterday, I can add them
to the page.
-- Jim
========================================================
James Crittenden Tel. (607) 255-9424
Wilson Synchrotron Laboratory Fax (607) 255-8062
Cornell University
Ithaca, New York 14853-8001
========================================================
David Rubin wrote:
There will be an RFA meeting tomorrow at 10:30 in Wilson large.
Dave