beamVelocityGen

beamVelocityGen Parameters

vbar (vector, default = 0)

Specifies the addition of a constant velocity to whatever velocity is returned from the specific kind of velocity generator. vbar can be specified for internal variables such as weight and tag, as well as the actual velocity components.

vsig (vector, default = 0)

Specifies the addition of a random velocity to whatever velocity is returned from the specific kind of velocity generator. The random velocity is sampled from a Gaussian with standard deviations for each component given by the value of vsig. The seed of the sampling can also be provided with the seed attribute. vsig can be specified for internal variables such as weight and tag, as well as the actual velocity components.

emissionQuad (integer, default = 0)

This defines the emission quadrant and thus the velocity directions based on which quadrant is selected. The default for this option is zero, in which case no emissionQuad check is performed on the particle velocities. The options are as follows:

• First quadrant (emissionQuad = 1)

  Velocities will be in the first quadrant, i.e. all positive.

• Second quadrant (emissionQuad = 2)

  Velocities will be in the second quadrant. The particle velocities in the x and y directions (V_0 and V_1) are negative and positive, respectively.

• Third quadrant (emissionQuad = 3)

  Velocities will be in the third quadrant, so V_0 will be negative and V_1 will also be negative.

• Fourth quadrant (emissionQuad = 4)

  Velocities will be in the fourth quadrant, so V_0 and V_1 will both be positive.

beamVelocityGen Example Block

<VelocityGenerator VelGen>
  kind = beamVelocityGen
  vbar = [VELOCITY 0.0 0.0]
  vsig = [0.0 0.0 0.0]
  emissionQuad = 1
</VelocityGenerator>