Visualizing lattices

Lattices can be visualized by serializing them into an HTML file. This can be done also via build.sequence_script by supplying the argument markup='html'. The resulting HTML sequence file can be viewed in any modern browser and elements can be inspected by using the browser’s inspector tool (e.g. <ctrl> + <shift> + C for Firefox).

Let’s visualize one of the example sequences:

>>> from importlib import resources
>>> from dipas.build import from_file, sequence_script
>>> import dipas.test.sequences
>>>
>>> with resources.path(dipas.test.sequences, 'cryring.seq') as path:
...     lattice = from_file(path)
...
>>> with open('cryring.html', 'w') as fh:
...     fh.write(sequence_script(lattice, markup='html'))
...

Note

The same result can also be obtained by using the madx-to-html command line utility that ships with the dipas package. Just run madx-to-html cryring.seq to generate a corresponding cryring.html file. Running madx-to-html --help shows all options for the utility.

This produces the following HTML page, as viewed from the browser:

../_images/cryring.png

Using the browser’s inspector tool we can inspect the elements and view their attributes:

../_images/cryring_inspector.png

Legend: The following information is encoded in the visualization:

  • Drift spaces are displayed as >,

  • Kickers are displayed as diamonds; the letters “H”, “V”, “T” indicate the type of kicker (no letter indicates a bare KICKER).

  • RBend, SBend, Quadrupole and Sextupole are displayed by their number of coils; for RBend and SBend those are displayed as two horizontal bars, the letters “R”, “S” indicate the type of magnet.

  • Monitors and Instruments are displayed as rectangles,

  • HKicker, VKicker, Quadrupole, Sextupole, RBend and SBend elements are displayed in blue if their particular main multipole component (hkick, vkick, k1, k2, angle and angle) has a positive sign (except for RBend and SBend, where the sign is inverted, because a positive angle bends towards negative x-direction), are displayed in red if that component is negative (with the exception of RBend and SBend again) and are displayed in grey if that component is zero. A further exception are quadrupoles with k1 == 0 which are displayed as drift spaces (>).

  • Kicker and TKicker elements are always displayed in blue,

  • Elements that do not actively influence the trajectory of the beam are displayed in grey (such as monitors, instruments),

  • Placeholders are displayed as drift spaces,

  • Markers are displayed as blank elements.

Plotting lattices and Twiss parameters

Lattices can be plotted together with Twiss parameters by using the plot.plot_twiss function. As an alternative, the DiPAS distribution also provides a command-line interface for doing that:

dipas plot path/to/script.madx

The resulting plot is interactive, specifically hovering over lattice elements will show their label as well as plot a guiding line to indicate their s-position in the plot:

../_images/example_plot.png

The plot is generated with matplotlib and depending on the plot-backend, e.g. PyQt5, it supports various other features such as zooming or panning of axes.