5.0 KiB
| title | section |
|---|---|
| BEAMDATA.txt | 5 |
NAME
beamdata.txt --- beam launcher data for gray(1)
FORMAT
The beam launcher data can be provided in three ways, each with a corresponding file format.
0D format
The beam parameters are given as fixed numbers, independent of the values of the launch angles α, β. In this case the format is as follows:
f ! comment
x₀ y₀ z₀
w₀₁ w₀₂ d₀₁ d₀₂ φ
where:
- f is the frequency (GHz)
- x₀, y₀, z₀ are the launcher position (cm)
- w₀₁, w₀₂ are the beam waists in the two principal directions (cm)
- d₀₁, d₀₂ are the distances of the beam waists from the launch point (cm)
- φ is the rotation angle from the horizontal direction to the first principal direction (deg)
Note: this case implies simple astigmatism, i.e. the amplitude and phase ellipses in the beam transverse plane are aligned.
1D format
The beam parameters, including the launch position and angles, are given as a function of the launcher steering angle θ in tabular format. The data will be interpolated by GRAY to obtain the actual beam parameters at a given pair of launch angles.
The format is as follows:
f ! comment
nrows
θ α β x₀ y₀ z₀ w₁ w₂ k₁ k₂ φ_w φ_R
θ α β x₀ y₀ z₀ w₁ w₂ k₁ k₂ φ_w φ_R
...
The first two lines contain the frequency (GHz) and the number of table rows. The rest of the file contains the whitespace-separated records, one row per line, where:
- θ is the mechanical steering angle (unused)
- α, β are the poloidal and toroidal launch angles (deg)
- x₀, y₀, z₀ are the launcher position (mm)
- w₁, w₂ are the beam widths in the two principal directions (mm)
- k₁, k₂ are the wavefront curvatures in the two principal directions (mm⁻¹)
- φ_w, φ_R are the rotation angles of the amplitude and phase ellipses in the transverse plane at the launch point (deg)
2D format
The beam parameters, including the launch position, are given as a function of the two launch angles α, β. The format is as follows:
nbeams
id mode f na nb
α β x₀ y₀ z₀ w₁ w₂ k₁ k₂ φ_w φ_R
α β x₀ y₀ z₀ w₁ w₂ k₁ k₂ φ_w φ_R
...
id mode f na nb
α β x₀ y₀ z₀ w₁ w₂ k₁ k₂ φ_w φ_R
α β x₀ y₀ z₀ w₁ w₂ k₁ k₂ φ_w φ_R
...
The first line specifies the number of beams described by the file. The rest of the files consists of nbeams 2D tables preceded by a header where:
- id is a string identifier of the beam
- mode indicates where the beam has O-mode (1) or X-mode (2) polarisation
- f is the frequency (GHz)
- nα, nβ are the numbers of rows and columns of the table
The 2D table is stored in row-major order over nα×nβ lines, that is, the i,j-th record is stored on the l-th line, with l = i + nα×j. The poloidal angle α(i,j) must be monotonic along i and the toroidal angle β(i, j) must be monotonic along j. Each line stores one record with the same fields as in the 1D format.
Note: even if this format allows to define multiple independent beams in the same file, this feature is not used by gray(1), which always load the first table.
EXAMPLES
-
A valid 0D beamdata.txt file
170 ! f 950.0 0.0 62.0 ! x₀ y₉ z₀ 2.1 2.1 162.0 162.0 0.0 ! w₀₁ w₀₂ d₀₁ d₀₂ φ -
A valid 1D beamdata.txt file
170 ! f 27 ! nrows -7.5 25.93 19.75 7067.6 -41.45 4233.6 42.70 43.99 -5.899E-4 -5.363E-4 -3.15 -3.15 -5.0 31.23 19.99 7067.8 -41.48 4233.6 42.70 43.99 -5.899E-4 -5.364E-4 -2.32 -2.32 -2.0 37.61 20.09 7068.1 -41.51 4233.5 42.69 43.98 -5.900E-4 -5.364E-4 -1.09 -1.09 3.5 49.29 19.77 7068.7 -41.58 4233.2 42.67 43.97 -5.902E-4 -5.366E-4 -2.11 -2.11 -
A valid 2D beamdata.txt file
1 ! nbeams example 1 137.6 6 2 ! id mode f nα nβ -7.96 -12.99 4352 -161.2 907 16.46 28.67 -2.48E-05 -2.36E-03 -21.79 5.61 4.82 -13.18 4392 -149.4 976 15.80 26.29 -4.71E-05 -2.56E-03 -17.88 8.85 14.52 -13.40 4416 -138.6 1031 15.30 24.50 -1.72E-04 -2.80E-03 -14.87 11.95 24.86 -13.70 4438 -125.4 1091 14.92 22.66 -4.36E-04 -3.19E-03 -11.63 15.84 36.12 -14.12 4455 -109.2 1159 14.90 20.80 -8.64E-04 -3.81E-03 -8.29 20.21 48.76 -14.72 4466 -89.0 1235 15.74 18.91 -1.38E-03 -4.80E-03 -7.66 23.62 -9.80 -6.93 4353 -132.0 904 16.71 29.36 -1.71E-04 -2.28E-03 -10.02 8.52 2.84 -7.14 4392 -123.8 972 16.03 26.82 -1.85E-04 -2.46E-03 -7.62 10.46 12.39 -7.38 4416 -116.4 1025 15.53 24.95 -3.05E-04 -2.67E-03 -5.78 12.41 22.50 -7.72 4437 -107.4 1084 15.13 23.06 -5.55E-04 -2.99E-03 -3.79 14.90 33.42 -8.18 4454 -96.5 1149 14.57 21.17 -9.75E-04 -3.51E-03 -10.43 14.82 45.51 -8.80 4465 -83.0 1222 15.65 19.32 -1.48E-03 -4.35E-03 0.41 20.57