Search found 1538 matches

by michael_borland
30 Jun 2020, 15:03
Forum: Ring Tracking
Topic: Tracking a beam coming from linac in to booster
Replies: 3
Views: 41

Re: Tracking a beam coming from linac in to booster

Arahim, I found a few other problems You were not computing the rf frequency accurately enough. This causes momentum offsets that can change the damping rate significantly. I added statements to address this. Your initial beam is spread over several buckets, so there are particles outside the bucket...
by michael_borland
30 Jun 2020, 13:18
Forum: Ring Tracking
Topic: Tracking a beam coming from linac in to booster
Replies: 3
Views: 41

Re: Tracking a beam coming from linac in to booster

Arahim,

I think it is just a matter of your damping time being extremely long (probably seconds) at 200 MeV. You only tracked for 3000 turns.

--Michael
by michael_borland
30 Jun 2020, 12:49
Forum: General
Topic: tuneshift with amplitude
Replies: 1
Views: 22

Re: tuneshift with amplitude

I've attached a example that may help.

Please note that higher-order coefficients are not always reliable due to the difficulty of identifying and determining tunes when there is motion is both planes at larger amplitudes.

--Michael
by michael_borland
30 Jun 2020, 09:58
Forum: Linac Tracking
Topic: Beam with higher order dispersion
Replies: 1
Views: 32

Re: Beam with higher order dispersion

Farzad, We don't have a tool for that, but you can add it by hand. E.g., sddsprocess beam0.sdds beam1.sdds \ "-define=parameter,etax2,1,units=m" "-define=parameter,etax3,0.1,units=m" \ "-define=column,delta,p pCentral / 1 -" \ "-redefine=column,x,x etax2 delta sqr * + etax3 delta 3 pow * +,units=m" ...
by michael_borland
30 Jun 2020, 09:54
Forum: Optimization and Matching
Topic: Sextupole magnet for correction of aberration with low energy spread
Replies: 2
Views: 45

Re: Sextupole magnet for correction of aberration with low energy spread

Seong-Yeol, I don't see a huge difference between the cases with and without energy spread. When the sextupoles are on, I do see a noticeable increase in emittance. I guess this is from the T111 matrix element, which becomes very large when the sextupoles are on. comparison.png Tijk.png --Michael
by michael_borland
30 Jun 2020, 09:33
Forum: Linac Tracking
Topic: no momentum-spread increase in several CSRDRIFTs with LSC on
Replies: 2
Views: 49

Re: no momentum-spread increase in several CSRDRIFTs with LSC on

Norio,

The problem may be that there is no CSRCSBEND in the lattice, or you don't have a CHARGE element. If you want LSC without CSR, use the LSCDRIFT element.

--Michael
by michael_borland
30 Jun 2020, 09:32
Forum: General
Topic: saving trajectory associated with macroparticle(s)
Replies: 2
Views: 40

Re: saving trajectory associated with macroparticle(s)

Philippe, Unfortunately, no. The best I can suggest is the following Add WATCH elements after all locations of interest. The insert_elements command can help with that. Use the START_PID and END_PID parameters on the WATCH elements to limit the output to a few interesting particles. This requires th...
by michael_borland
30 Jun 2020, 09:08
Forum: Linac Tracking
Topic: custom interval for slice_analysis and SLICE element
Replies: 1
Views: 18

Re: custom interval for slice_analysis and SLICE element

1. Is it possible to define custom time interval and fixed bin size for slice_analysis and SLICE element ? Unfortunately not, and it would be quite complex to add this feature. I suggest setting N_SLICES to a large value and then post-processing to average over various numbers of slices as a way to...
by michael_borland
10 Jun 2020, 18:31
Forum: General
Topic: Electron beam optics after Undulator using a dogleg type achromatic bend
Replies: 4
Views: 117

Re: Electron beam optics after Undulator using a dogleg type achromatic bend

Sarvesh, I can see several possible problems. First, although you are trying to make etax(s) antisymmetric about the Q2 magnet, your dipoles are not antisymmetric, since B1 has ANGLE<0, E1>0, and E2>0, while B2 has ANGLE>0, E1>0, E2>0. So there's no way to get the solution you want. Maybe you mean t...
by michael_borland
10 Jun 2020, 18:00
Forum: Ring Tracking
Topic: Closed orbit for off-momentum particles
Replies: 2
Views: 53

Re: Closed orbit for off-momentum particles

David, The calculation starting from the beam centroids won't give you the result you want. Basically, the beam centroinds are only taken as a hint of the closed orbit location. It's not one of the more useful features in elegant, to be honest. Is there a reason that the MALIGN approach isn't suffic...