Search found 1800 matches

by michael_borland
06 Feb 2023, 13:48
Forum: Bugs
Topic: Impossible to set ignored_portion less than 1e-5 in touschek_scatter function
Replies: 1
Views: 117

Re: Impossible to set ignored_portion less than 1e-5 in touschek_scatter function

Mikhail, I see in the code that values less than or equal to 1e-6 are treated as zero. I think the assumption was that for ~1 million particles, the algorithm that ignores particles probably doesn't give very precise results when ignored_portion is so small. However, it shouldn't hurt anything, so I...
by michael_borland
06 Feb 2023, 11:27
Forum: Bugs
Topic: Misalignment of a tilted csbend
Replies: 3
Views: 98

Re: Misalignment of a tilted csbend

Zhe, I think I've fixed these issues, using an approach similar to what you tried, but in a way that applies also to other elements. In the end, I had to disable the "exact" misalignment subroutines used by the tracking routines and use the versions that are linear in the errors. There's a bug in my...
by michael_borland
31 Jan 2023, 19:54
Forum: Bugs
Topic: Misalignment of a tilted csbend
Replies: 3
Views: 98

Re: Misalignment of a tilted csbend

Zhe,

Thanks, I'll check it out and let you know.

--Michael
by michael_borland
30 Jan 2023, 10:14
Forum: Linac Tracking
Topic: How to change the KQUAD from K1 to pole tip field?
Replies: 1
Views: 77

Re: How to change the KQUAD from K1 to pole tip field?

Cai, If you want to compute the pole-tip field after the fact, you can use data in the parameter file (obtained via the parameters field in run_setup) as in sddsprocess run.param run.Btip -match=column,ElementParameter=K1 \ -define=parameter,H,"<energyInGeV> 1e9 * c_mks /",units=T*m \ -define=col,Bt...
by michael_borland
30 Jan 2023, 10:09
Forum: Ring Tracking
Topic: rf feedback in rfmode element
Replies: 3
Views: 150

Re: rf feedback in rfmode element

Chao,

Your understanding of the cascaded filters is correct. There's a typo in your message
y[n] = \sum a_i y_{i-1} + \sum b_i y_{i-1}
should be
y[n] = -\sum a_i y_{i-1} + \sum b_i x_{i-1}

--Michael
by michael_borland
30 Jan 2023, 10:01
Forum: General
Topic: Centroid Shift without any magnet alignment error
Replies: 2
Views: 114

Re: Centroid Shift without any magnet alignment error

Without a lattice file it isn't possible to say what the problem might be.

--Michael
by michael_borland
09 Dec 2022, 15:50
Forum: Ring Tracking
Topic: rf feedback in rfmode element
Replies: 3
Views: 150

Re: rf feedback in rfmode element

Chao, Your understanding of the basic process is correct. The filter coefficients are dimensionless. For the voltage feedback, the voltage error is multiplied by 2(1+beta)/Ra to convert it to a current error. There is no separate gain control. The filter coefficients determine the gain. The manual p...
by michael_borland
29 Nov 2022, 09:45
Forum: Ring Tracking
Topic: modulate_elements command
Replies: 2
Views: 121

Re: modulate_elements command

Pradeep, To understand the expression, you should first realize that before the expression is executed, the beam arrival time (Ct) is pushed onto the stack. In the example, T0=3.68e-6 is the revolution time, so "3.68e-6 /" results in the turn number (Ct/T0) being on the top of the stack. We then div...
by michael_borland
28 Nov 2022, 17:21
Forum: General
Topic: FodoCell
Replies: 2
Views: 154

Re: FodoCell

Perhaps the attached example will help.

--Michael
by michael_borland
18 Nov 2022, 18:43
Forum: Ring Tracking
Topic: RFMODE with multiple bunches
Replies: 4
Views: 2319

Re: RFMODE with multiple bunches

Sara, I identified several issues The bunch interval (duplicate_stagger in makeBeam.ele) is wrong for your 500 MHz rf system. It should be a multiple of 1/MainRfFrequency. The Q of your harmonic cavity is very high. Even for SC cavities, we need to load the cavity to prevent very high beam-induced v...