The OPAL Discussion Forum

[Andreas Adelmann <andreas.adelmann AT psi.ch>]

Hello Chris please update OPAL I have solved the DC-Gun autophase problem.

APVETO is already found his way into the documentation :-) 

The attribute APVETO prevents the element from being autophased and takes the LAG as actual phase.

For you problem (gun_NOAP_problem) the modification would look like this:

IN.GUN: rfcavity, l = 1.50000E-01, fmapfn = "fieldgrid_1.t7", volt = 1.39623E+01, elemedge = 0.0, lag = PI, APVETO=TRUE;

Then you get the following from the single particle tracking:

Ippl> start phase scan ... 

Autophasing >  ----> APVETO -----> IN.GUN

Ippl> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Ippl> IN.GUN, start Ekin= 0 MeV, t= 0 s, phi= 3.14159, 

Ippl> beta = 0.0001 tErr = -3.33564e-11

Autophasing > Did APtrack with phi= 3.14159 result E= 0.500001

Autophasing > IN.GUN_phi= 0 rad / 0 deg, AstraPhi= 90 deg,

Autophasing > E= 0 (MeV), phi_nom= 180

Ippl> step = 0, spos = 1.12048e-06 [m], t= 5e-13 [s], E= 6.60289e-07 [MeV] 

Ippl> step = 1000, spos = 0.0907661 [m], t= 5.005e-10 [s], E= 0.499679 [MeV] 

OPAL > 

OPAL > -------------------------------------------------------------------------------------

OPAL > IN.GUN: phi_orig= phi_nom + phi_maxE= 180 degree, global phase shift= -0 degree

OPAL > -------------------------------------------------------------------------------------

and with your read in distribution:

OPAL > 14.00.07 Step 747 at 0.154788 [m] t= 7.48e-10 [s] E=0.499998 [MeV] 

OPAL > * Wrote beam phase space.

OPAL > * ************** B U N C H ********************************************************* 

OPAL > * NP= 27 Qtot= 0.0027 [nC]  Qi= 1e-13 [C]

OPAL > * Ekin= 0.499998 [MeV] dEkin= 4.42735e-06 [MeV]

OPAL > * rmax= ( 4.78212e-07 , 4.78212e-07 , 0.154789 ) [m]

OPAL > * rmin= ( -4.78212e-07 , -4.78212e-07 , 0.154787 ) [m]

OPAL > * rms beam size= ( 3.90362e-07 , 3.90362e-07 , 1.07762e-06 ) [m]

OPAL > * rms momenta= ( 1.6892e-06 , 1.6892e-06 , 1.00411e-05 ) [beta gamma]

OPAL > * mean position= ( -2.74501e-23 , 3.92145e-24 , 0.154788 ) [m]

OPAL > * mean momenta= ( 6.27432e-23 , 0 , 1.70715 ) [beta gamma]

OPAL > * rms emittance= ( 2.49498e-16 , 2.49498e-16 , 7.50314e-14 ) (not normalized)

OPAL > * rms correlation= ( -1 , -1 , -0.99993 )

OPAL > * dh= 0 [m] dT= 1e-12 [s]

OPAL > * hr= ( 6.37616e-08 , 6.37616e-08 , 1.78814e-07 ) [m]

OPAL > * spos= 0.154788 [m]

OPAL > * ********************************************************************************** 

See the modified file in the attachment.

Cheers Andreas 

Attachment: gun_NOAP_problem.tgz
Description: Binary data

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Dr. sc. math. Andreas (Andy) Adelmann
Staff Scientist
Paul Scherrer Institut WLGB/132 CH-5232 Villigen PSI
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