Simple Bmad lattice
The following is a very simple Bmad lattice:
beginning[beta_a] = 10. ! m a-mode beta function
beginning[beta_b] = 10. ! m b-mode beta function
beginning[e_tot] = 10e6 ! eV Or can set p0c
parameter[geometry] = open ! or closed
parameter[particle] = electron ! Default is positron
d: drift, L = 0.5
b: sbend, L = 0.5, g = 1 ! g = 1 / bending_radius
q: quadrupole, L = 0.6, k1 = 0.23
lat: line = (d, b, q) ! List of lattice elements
use, lat ! Line used to construct the lattice
Using the above as content, create a file 'lat.bmad' and run tao on the command line:
> tao -lat lat.bmad
A plot window should be created looking like:
Notes:
- Use the -no_plot option when starting Tao to avoid creating a plot window.
- Use the -geometry option to get a smaller plot window. Example: -geom 400x500
- Bmad lattice file syntax is generally case insensitive (file names are an exception).
- Tao commands are case sensitive.
- Multiple lines may be specified. And lines may contain sublines.
- The line used to construct the lattice is determined by the use statement.
Tao> help
Type 'help <command>' for help on an individual command
Available commands:
alias read
call restore
change reinitialize
clip run_optimizer
continue scale
derivative set
end_file show
exit single_mode
flatten spawn
... etc...
For instance:
Tao> help set
The "set" command is used to set values for data,
variables, etc. Format:
set beam_init {n@}<component> = <value>
set beam_start {n@}<coordinate> = <value>
set bmad_com <component> = <value>
set csr_param <component> = <value>
set curve <curve> <component> = <value>
set data <data_name>|<component> = <value>
set default <parameter> = <value>
set element <element_list> <attribute> = <value>
set floor_plan <component> = <value>
set geodesic_lm <component> = <value>
set global <component> = <value>
set graph <graph> <component> = <value>
set key <key> = <command>
set lat_layout <component> = <value>
set lattice {n@}<destination_lat> = <source_lat>
set opti_de_param <component> = <value>
set plot <plot> <parameter> = <value>
set plot_page <parameter> = <value1> {<value2>}
set ran_state = <random_number_generator_state>
set universe <what_universe> <on/off>
set universe <what_universe> recalculate
set universe <what_universe> mat6_recalc <on/off>
set universe <what_universe> track_recalc <on/off>
set variable <var_name>|<component> = <value>
set wave <component> = <value>
Also see the "change" command . The "change" command is specialized
for varying real parameters while the "set" command is more general.
... etc...
Use the command:
help set <what>
to obtain more information on a particular set subtopic. Example:
help set plot
Tao> show lat
Values at End of Element:
Index name key s l beta phi eta orbit beta phi eta orbit Track_State
a a a x [mm] b b b y [mm]
0 BEGINNING Beginning_Ele 0.000 --- 10.00 0.000 0.00 0.000 10.00 0.000 0.00 0.000 Alive
1 D Drift 0.500 0.500 10.03 0.050 0.00 0.000 10.03 0.050 0.00 0.000 Alive
2 B Sbend 1.000 0.500 7.87 0.104 0.12 0.000 10.00 0.100 0.00 0.000 Alive
3 Q Quadrupole 1.600 0.600 3.50 0.217 0.40 0.000 10.64 0.159 0.00 0.000 Alive
4 END Marker 1.600 0.000 3.50 0.217 0.40 0.000 10.64 0.159 0.00 0.000 Alive
Index name key s l beta phi eta orbit beta phi eta orbit Track_State
a a a x [mm] b b b y [mm]
Values at End of Element:
Bmad adds two extra elements to the lattice. A zero length beginning element called BEGINNING and a zero length marker element at the end called END.
Note: "show lat" (like many other commands) has lots of optional parameters to customize the table of information printed.
Tao> help show lat
Syntax:
show lattice {-0undef} {-all} {-attribute <attrib>} {-base}
{-blank_replacement <string>} {-branch <name_or_index>}
{-custom <file_name>} {-design} {-floor_coords} {-lords} {-middle}
{-no_label_lines} {-no_tail_lines} {-no_slaves} {-orbit} {-radiation_integrals}
{-remove_line_if_zero <column #>} {-s <s1>:<s2>} {-tracking_elements}
{<element_list>}
Show a table of Twiss and orbit data, etc. at the specified element locations. The default
is to show the parameters at the exit end of the elements. To show the parameters in the
... etc...
Tao> show ele b ! or: show ele 2
Element # 2
Element Name: B
Key: Sbend
Sub Key: SBend
S_start, S: 0.500000, 1.000000
Ref_time: 3.340005E-09
Attribute values [Only non-zero/non-default values shown]:
1 L = 5.0000000E-01 m
6 G = 1.0000000E+00 1/m
8 RHO = 1.0000000E+00 m
13 SPIN_FRINGE_ON = T (1)
19 E1 = 0.0000000E+00 rad
20 E2 = 0.0000000E+00 rad
29 L_SAGITTA = 3.1087578E-02 m
... etc...
Twiss at end of element:
A B Cbar C_mat
Beta (m) 7.87064432 9.99974729 | 0.00000000 0.00000000 0.00000000 0.00000000
Alpha 3.93634109 0.20027369 | 0.00000000 0.00000000 0.00000000 0.00000000
Gamma (1/m) 2.09573455 0.10401358 | Gamma_c = 1.00000000 Mode_Flip = F
Phi (rad) 0.10395730 0.09991742 X Y Z
Eta (m) 0.12241744 0.00000000 0.12241744 0.00000000 -0.01796326
Etap 0.48187421 0.00000000 0.48187421 0.00000000 0.00000000
Orbit: Positron State: Alive
Position[mm] Momentum[mrad] Spin |
X: 0.00000000 0.00000000 | Particle [sec]: 3.34000451E-09 E_tot; 1.0000E+07
Y: 0.00000000 0.00000000 | Part-Ref [sec]: 0.00000000E+00 PC: 9.9869E+06
Z: 0.00000000 0.00000000 | (Ref-Part)*Vel [m]: 0.00000000E+00 Beta: 0.998694
Note: By default, only non-zero attributes are shown. Use the -all option to see all the attributes.
Show all elements whose name begins with "Q":
Tao> show ele q*
1 Q 1.000
Number of Matches: 1
Show all sbend elements:
Tao> show ele sbend::*
2 B 2.000
Number of Matches: 1
General syntax:
show ele <element_type>::<name_with_wild_card_characters>
Wild card characters are
- "*" -- Matches to any number of characters.
- "%" -- Matches to any single character.