Dynamic aperture scan in x direction with a y offset

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gwei
Posts: 33
Joined: 17 Jul 2015, 07:16

Dynamic aperture scan in x direction with a y offset

Post by gwei » 24 Jan 2017, 16:37

Hello, Michael, and other experts,

Usually we make dynamic aperture line survey as shown in follow figure.
DAline-survey.jpg
line survey of dynamic aperture
And we can use like follow words to get the dynamic aperture for the line (X= n*sigma_x, Y=n*sigma_y), (X= -n*sigma_x, Y=n*sigma_y)
and (X= 0*sigma_x, Y=n*sigma_y).
&find_aperture
output = "%s.aper",
mode = n-lines,
n_lines = 41,
xmin = -0.001,
xmax = 0.001,
ymin = 0
ymax = 0.0005,
nx = 21,
ny = 11,
n_splits = 5,
desired_resolution = 0.00001,
verbosity = 1
&end

But for the line (X= n*sigma_x, Y=1*sigma_y), I don't know how to make the dynamic aperture scan.
And when I make a scan with the line (X= n*sigma_x, Y=0*sigma_y), I can only get a result of NO 3 of follow figures which is not enough.
DAresultOfDifferentLine.png
Thank you.

Guohui

michael_borland
Posts: 1801
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
Contact:

Re: Dynamic aperture scan in x direction with a y offset

Post by michael_borland » 25 Jan 2017, 10:19

Guohui,

If I understand correctly, you want to set the initial y coordinate to a fixed value and scan the x coordinate to find the aperture. You can do this by simply creating a line of particles in phase space, e.g.,

Code: Select all

&bunched_beam
	n_particles_per_bunch = 100,
	bunch = %s.bun,
	! 20mm horizontal size
	beta_x = 2e300,
	emit_x = 2e-304,
	! Zero vertical size
	beta_y = 1,
	emit_y = 0,
	! 1mm vertical offset
	centroid[2] = 1e-3
	! Distribution is a line in x-x' and y-y' phase space
	distribution_type[0] = 2*"line"
&end
In addition, in the &run_setup command, you should request the acceptance output:

Code: Select all

&run_setup
...
acceptance = %s.acc
...
&end
The .acc file will contain the initial coordinates of all particles that survive tracking, which is the aperture in this case.

--Michael

gwei
Posts: 33
Joined: 17 Jul 2015, 07:16

Re: Dynamic aperture scan in x direction with a y offset

Post by gwei » 25 Jan 2017, 10:39

--
Last edited by gwei on 25 Jan 2017, 10:43, edited 1 time in total.

gwei
Posts: 33
Joined: 17 Jul 2015, 07:16

Re: Dynamic aperture scan in x direction with a y offset

Post by gwei » 25 Jan 2017, 10:42

michael_borland wrote:Guohui,

If I understand correctly, you want to set the initial y coordinate to a fixed value and scan the x coordinate to find the aperture. You can do this by simply creating a line of particles in phase space, e.g.,

Code: Select all

&bunched_beam
	n_particles_per_bunch = 100,
	bunch = %s.bun,
	! 20mm horizontal size
	beta_x = 2e300,
	emit_x = 2e-304,
	! Zero vertical size
	beta_y = 1,
	emit_y = 0,
	! 1mm vertical offset
	centroid[2] = 1e-3
	! Distribution is a line in x-x' and y-y' phase space
	distribution_type[0] = 2*"line"
&end
--Michael
Thank you, Michael

And what's the meaning of ' centroid[2] = 1e-3 ' ? a y offset=0.001 m ?
In your definition of centroid, it is
double centroid[6] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0};
And I guess {0.0, 0.0, 0.0, 0.0, 0.0, 0.0} is values in (x, x’, y, y’, t, p)
Is it right?

Best wishes

Guohui

michael_borland
Posts: 1801
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
Contact:

Re: Dynamic aperture scan in x direction with a y offset

Post by michael_borland » 25 Jan 2017, 13:11

Guohui,
And what's the meaning of ' centroid[2] = 1e-3 ' ? a y offset=0.001 m ?
In your definition of centroid, it is
double centroid[6] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0};
And I guess {0.0, 0.0, 0.0, 0.0, 0.0, 0.0} is values in (x, x’, y, y’, t, p)
Is it right?
Yes, that's all correct, except centroid[4] and centroid[5], which are in units of meters and fractional momentum deviation, respectively.

--Michael

gwei
Posts: 33
Joined: 17 Jul 2015, 07:16

Re: Dynamic aperture scan in x direction with a y offset

Post by gwei » 25 Jan 2017, 13:59

michael_borland wrote:Guohui,
And what's the meaning of ' centroid[2] = 1e-3 ' ? a y offset=0.001 m ?
In your definition of centroid, it is
double centroid[6] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0};
And I guess {0.0, 0.0, 0.0, 0.0, 0.0, 0.0} is values in (x, x’, y, y’, t, p)
Is it right?
Yes, that's all correct, except centroid[4] and centroid[5], which are in units of meters and fractional momentum deviation, respectively.

--Michael
So centroid[0] means x, centroid[1] means x', centroid[2] means y, centroid[3] means y', centroid[4] means t, centroid[5] means p.
if we want a centroid offset of x = 0.001 m and y = 0.001 m ,
we should write : centroid[0, 2] ={1e-3, 1e-3}. Is it right?

michael_borland
Posts: 1801
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
Contact:

Re: Dynamic aperture scan in x direction with a y offset

Post by michael_borland » 25 Jan 2017, 17:10

Guohui,
So centroid[0] means x, centroid[1] means x', centroid[2] means y, centroid[3] means y', centroid[4] means t, centroid[5] means p.
if we want a centroid offset of x = 0.001 m and y = 0.001 m ,
we should write : centroid[0, 2] ={1e-3, 1e-3}. Is it right?
That's not quite right. centroid[4] is distance traveled, not time, while centroid[5] is (p-<p>)/<p>, not p itself. The syntax for changing several centroids is

Code: Select all

centroid[0] = 1e-3
centroid[2] = 1e-3,
or

Code: Select all

centroid[0] = 1e-3, 0, 1e-3
--Michael

gwei
Posts: 33
Joined: 17 Jul 2015, 07:16

Re: Dynamic aperture scan in x direction with a y offset

Post by gwei » 26 Jan 2017, 09:25

michael_borland wrote:Guohui,
So centroid[0] means x, centroid[1] means x', centroid[2] means y, centroid[3] means y', centroid[4] means t, centroid[5] means p.
if we want a centroid offset of x = 0.001 m and y = 0.001 m ,
we should write : centroid[0, 2] ={1e-3, 1e-3}. Is it right?
That's not quite right. centroid[4] is distance traveled, not time, while centroid[5] is (p-<p>)/<p>, not p itself. The syntax for changing several centroids is

Code: Select all

centroid[0] = 1e-3
centroid[2] = 1e-3,
or

Code: Select all

centroid[0] = 1e-3, 0, 1e-3
--Michael
Thank you very much! Michael

Guohui

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