uspas02.inp

pic 模拟程序！面向对象

uspas02
{

This input file, uspas02.inp, was written by David Bruhwiler
for "Object Oriented Computational Accelerator Physics," a
two week course presented at the University of Colorado for
the U.S. Particle Accelerator School in June, 2001.

Here, we model a quiescent electron plasma, with a uniform
  background of stationary ions, in Cartesian geometry.
Low resolution and few particles are used here for testing purposes.

Boundary conditions:
  The simulation region is bounded by perfect conductors.  This is
  not optimal, but it correctly handles the issue of particles that
  exit the simulation.

Topics for discussion:
  a) How are the plasma electrons initialized?
  b) What is the particle distribution in x, y, Ux, Uy?
  c) What sort of fields are generated by the plasma?
  d) What is happening at the boundaries?
  e) What happens if the plasma frequency is not resolved?
}

// Define variables that can be used throughout this input file.

Variables
{
// First, define some useful constants.
  speedOfLight = 2.99792458e+08
  electronMass = 9.1093897e-31
  unitCharge = electronMass * 1.75881962e11
  electronCharge = -1. * unitCharge
  electronMassEV = electronMass * speedOfLight * speedOfLight / unitCharge
  ionCharge = unitCharge
  unitMassMKS = electronMass / 5.48579903e-04
  lithiumMassNum = 6.942
  lithiumMass = unitMassMKS * lithiumMassNum

// Define the number of grids in X and Y
  numYgrids = 64
  numXgrids = 64
  numCells = numXgrids * numYgrids

// Calculate the size of the simulation region, grid spacings, time step.
  xGridSize = 0.001
  maxLengthMKS = numXgrids * xGridSize
  yGridSize = 0.001
  maxWidthMKS = numYgrids * yGridSize
  effGridSize = 1. / sqrt( 1./(xGridSize*xGridSize) + 1./(yGridSize*yGridSize) )
  timeStep = 0.9 * effGridSize / speedOfLight

// Define the plasma density, number of plasma electron macro-particles, etc.
  plasmaDensityMKS = 2.e20
  simulationVolume = maxWidthMKS * 1.0 * maxLengthMKS
  totalNumPlasma = plasmaDensityMKS * simulationVolume
  numPtclsPerCell = 4
  numPlasmaPtcls = numPtclsPerCell * numCells
  plasmaNumRatio = totalNumPlasma / numPlasmaPtcls
}

// This simulation has only one "region", which contains
//   the grid, all particles, etc.
Region
{

// Define the grid for this region.
Grid
{

// Define number of grids along X-axis and physical coordinates.
  J = numXgrids
  x1s = 0.0
  x1f = maxLengthMKS
  n1 = 1.0

// Define number of grids along Y-axis and physical coordinates.
  K = numYgrids
  x2s = 0.0
  x2f = maxWidthMKS
  n2 = 1.0

// Specify Cartesian geometry
  Geometry = 1
}

// Specify "control" parameters for this region
Control
{
// Specify the time step.
  dt = timeStep
}

// Define the plasma ions.
Species
{
  name = plasma_ions
  m = lithiumMass
  q = ionCharge
}

// Load the plasma ions over the entire simulation region.
Load
{
  speciesName = plasma_ions
  density = plasmaDensityMKS
  x1MinMKS = 0.0
  x1MaxMKS = maxLengthMKS
  x2MinMKS = 0.0
  x2MaxMKS = maxWidthMKS

// This specifies a static uniform background (no macro-particles).
  np2c = 0
}

// Define the plasma electrons.
Species
{
  name = plasma_electrons
  m = electronMass
  q = electronCharge
}

// Load the plasma electrons over the entire simulation region
Load
{
  speciesName = plasma_electrons
  density = plasmaDensityMKS
  x1MinMKS = 0.0
  x1MaxMKS = maxLengthMKS
  x2MinMKS = 0.0
  x2MaxMKS = maxWidthMKS
  np2c = 2 * plasmaNumRatio

// Specify loading that is more uniform than random
	LoadMethodFlag = 1
}

// Specify a perfect conductor along the left boundary.  This serves
//    as a particle boundary condition (catches particles that leave
//    the simulation) and as a field boundary condition (E_y is forced
//    to vanish).
Conductor
{
  j1 = 0
  j2 = 0
  k1 = 0
  k2 = numYgrids
  normal = 1
}

// Specify a perfect conductor along the top boundary.  This serves as a
//   particle boundary condition (catches particles that leave the simulation)
//   and as a field boundary condition (E_x is forced to vanish).
Conductor
{
  j1 = 0
  j2 = numXgrids
  k1 = numYgrids
  k2 = numYgrids
  normal = -1
}

// Specify a perfect conductor along the bottom boundary.  This serves as a
//   particle boundary condition (catches particles that leave the simulation)
//   and as a field boundary condition (E_x is forced to vanish).
Conductor
{
  j1 = 0
  j2 = numXgrids
  k1 = 0
  k2 = 0
  normal = 1
}

// Specify a perfect conductor along the right boundary.  This serves as a
//   particle boundary condition (catches particles that leave the simulation)
//   and as a field boundary condition (E_y is forced to vanish).
Conductor
{
  j1 = numXgrids
  j2 = numXgrids
  k1 = numYgrids
  k2 = 0
  normal = -1
}

}