Calculate a position on a field line.

Optionally, rather than strictly following the field line, you can weight so it stays closer to the starting position. This is done using the start_weight parameter. A value of 0 means that the function exactly follows the field line while a value of 1 means the x1 and x2 coordinates will be fixed to those of the start value. Values in between correspond to a weighted sum of these two options.

The distance returned will correspond to the distance along the weighted version of the field line (rather than the original one). That is, it will always be the same as the distance you would get from integrating along the curve returned by this function.

Parameters:¶

start: SliceCoord¶

The position of the field-line in the x1-x2 plane at x3 = 0.

x3: numpy.typing.ArrayLike¶

x3 coordinates at which to calculate the position of the field line

start_weight: float = 0.0¶

How much weight to apply to the start position versus the field line

Returns:¶

• The first element is the x1 and x2 coordinates of the field line at

• the provided x3 positions. The second is an array with the distance

• traveersed along the field line to those points.