pwfahe.inp

pic 模拟程序！面向对象

pwfaHe.inp
{

Here we look at the generation of a large-amplitude wakefield by a
very short ( < 50 fs), high intensity ( > 1e18 W/cm^2) laser pulse.
The pulse is so short, in order to make the simulation as fast as
possible for initial work.  We use a laser wavelength of 1 micron
and  and a minimum spot size of 5 micron in order to connect with
previous work by Rodolfo Giacone and Brad Shadwick.  Otherwise, the 
parameters are comparable to those used in the l'OASIS experiments 
at LBNL.

Pulse with transverse Gaussian profile and z polarization is launched from
the left boundary.  The longitudinal  profile is a truncated Gaussian.

Cartesian geometry, no plasma initially, background of neutral He gas.
The primary goal is to see how the plasma wake gets modified by the
fact that the laser pulse must create its own plasma.

This is derived from loasisHe.inp -- here we make the laser pulse
extremely short, change the size of the simulation region, change the
minimum spot size and laser wavelength somewhat, and also adjust the
He / electron density.
}

Variables
{
// General numerical parameters
  PI = 3.14159

// **********************************************************************
// General physical parameters
// **********************************************************************
  electronMass = 9.1094e-31 
  electronCharge = -1.6022e-19
  permit = 8.8542e-12 
  speedLight = 2.9979e8
  speedLight2 = speedLight*speedLight 
  electronCharge2 = electronCharge*electronCharge 
  qOverM = electronCharge/electronMass

  ionCharge = -electronCharge
  unitMassMKS = electronMass / 5.48579903e-04
  hydrogenMassNum = 1.00797
  hydrogenMass = unitMassMKS * hydrogenMassNum
  HeMassNum = 4.0026
  HeMass = unitMassMKS * HeMassNum

// **********************************************************************
// Plasma parameters
// **********************************************************************
//   Here, we have zero initial plasma density.
  elecPlasmaDensity =  0.0 
  elecPlasmaFreq = sqrt(electronCharge*qOverM*elecPlasmaDensity/permit)
 
// **********************************************************************
// Laser pulse parameters - y polarization
// **********************************************************************
//   We are modeling a laser pulse with wavelength of 0.8 micron, a
//   FWHM pulse length of 6.7 fs, a peak intensity of 3 x 10^18 W/cm^2
//   and a minimum laser spot size of 5 micron.
//
  peakLaserIntensity = 3e+18  // W/cm^2
  pulseLengthFWHM = 6.7e-15
  RMStoFWHMfactor = 2. * sqrt( ln(2.) )
  FWHMtoTotalFactor = sqrt( ln(2.) )
  pulseLengthRMS = pulseLengthFWHM / RMStoFWHMfactor
  pulseLengthTotal = pulseLengthFWHM * FWHMtoTotalFactor

  laserWavelength = 1.0e-06
  laserFrequency = 2.*PI*speedLight/laserWavelength

  // We must convert the intensity to MKS units
  peakLaserIntensityMKS = peakLaserIntensity * 1.0e+04
  peakElectricField = sqrt(2.*peakLaserIntensityMKS/speedLight/permit)

// **********************************************************************
// Grid parameters
// **********************************************************************
// We must resolve the laser wavelength
  Nx = 512
  Ny = 256

  Lx = 30.0e-06
  Ly = 50.0e-06

  dx = Lx / Nx
  dy = Ly / Ny

  d = 1. / sqrt( 1./(dx*dx) + 1./(dy*dy) )
  timeStep = 0.7 * d / speedLight

// **********************************************************************
// More laser parameters:
// **********************************************************************
// We model the laser pulse envelope as a Gaussian (nPulseShape=1).
  nPulseShape = 1
  pulseLength  = pulseLengthTotal * speedLight

// Here we specify the waist size, Rayleigh length, etc.
// These parameters are for a pulse with y-polarization.
  waistSize = 5.0e-06 
  angFreq = laserFrequency
  angFreq2 = angFreq * angFreq
  waveVector = sqrt( (angFreq2-elecPlasmaFreq*elecPlasmaFreq) / speedLight2 )
// For waistSize = 5e-6 and wavelength = 1e-6, the Rayleigh length is 78.5e-6
  rayleighLength = waistSize * waistSize * waveVector / 2.
  waistLocation = Lx

// **********************************************************************
// Define gas density, pressure and other MCC parameters
// **********************************************************************
  gasTempEV       = 1.0e-06  // make gas cold (cannot set temperature to zero)
  gasDensityMKS   = 1.5e25
  gasPressureTorr = 1.20e-21 * gasDensityMKS * gasTempEV

  numZeroCells = 50
  numFlatCells = Nx-100
  numRampCells = Nx - numFlatCells - numZeroCells
  zeroEnd = (numZeroCells + .5) * dx
  rampEnd = (numZeroCells + numRampCells + .5) * dx

// This is the desired delay time before the moving window algorithm activates.
  movingWindowDelay = (Nx-10) * dx / speedLight
}

Region
{
Grid
{
  J = Nx 
  x1s = 0.0
  x1f = Lx 
  n1 = 1.0 
  K = Ny 
  x2s = 0.0
  x2f = Ly 
  n2 = 1.0
  Geometry = 1
}

Control
{
  dt = timeStep

// Turn on the moving window algorithm.
  movingWindow = 1
  shiftDelayTime = movingWindowDelay
}

Species
{
  name = electrons
  m = electronMass 
  q = electronCharge 
  particleLimit = 2.0e+06 // prevents out-of-control growth in # of ptcls
}

Species
{
  name = HePlus
  m = HeMass
  q = ionCharge
  particleLimit = 2.0e+05 // prevents out-of-control growth in # of ptcls
}

Species
{
  name = HePlusPlus
  m = HeMass
  q = 2*ionCharge
  particleLimit = 9.0e+05 // prevents out-of-control growth in # of ptcls
}

// Specify the Monte Carlo collision parameters for background gas
MCC
{
  gas                         = He
  pressure                    = gasPressureTorr
  temperature                 = gasTempEV
  analyticF = gasDensityMKS * step(x1-zeroEnd) * ( ramp( (x1-zeroEnd)/(rampEnd-zeroEnd) ) * step(rampEnd-x1) + step(x1-rampEnd) )

  eSpecies                = electrons
  iSpecies                = HePlus
  iSpeciesPlusPlus        = HePlusPlus

  // turn OFF electron/ion collisions, including impact ionization
  collisionFlag = 0

  // turn on tunneling ionization in linearly polarized alternating field
  tunnelingIonizationFlag = 1
  // specify static field / circular polarization
  ETIPolarizationFlag     = 1
  // specify the characteristic oscillation frequency of the electric field
  // -- here we fudge the real frequency with a small factor --
  EfieldFrequency =  laserFrequency
  // fix the number of macro particles to be created in each cell
  TI_numMacroParticlesPerCell = 8
}
Diagnostic
{
	j1 = 0
	j2 = Nx
	k1 = 0
	k2 = Ny
	VarName = WaveDirDiagnostic
        polarizationEB = EzBy
        psd1dFlag = 1 // calculate the 1d power spectral density
        windowName = Blackman
	title = Wave Energy
	x1_Label = x
	x2_Label = y
	x3_Label = Wave Energy
}

PortGauss
{
  j1 = 0 
  k1 = 0 
  j2 = 0 
  k2 = Ny 
  normal = 1

  A = 0
  C = 1.0 

// Wave (0)
  pulShp_p0 = nPulseShape
  tdelay_p0 = 0.0 
  pulLeng_p0 = pulseLength
  chirp_p0 = 0.0
  spotSize_p0 = waistSize
  waveLeng_p0 = laserWavelength
  focus_p0 = waistLocation
  amp_p0 = 0.0

// Wave (1)
  pulShp_p1 = nPulseShape
  tdelay_p1 = 0.0
  pulLeng_p1 = pulseLength
  chirp_p1 = 0.0
  spotSize_p1 = waistSize
  waveLeng_p1 = laserWavelength
  focus_p1 = waistLocation
  amp_p1 = peakElectricField

  EFFlag = 0 
  name = PortGauss
}


ExitPort
{
  j1 = 0
  k1 = Ny 
  j2 = Nx 
  k2 = Ny 
  normal = -1
  EFFlag = 0 
  name = ExitPort
  C = 0
  A = 0
}

ExitPort
{
  j1 = 0
  k1 = 0 
  j2 = Nx 
  k2 = 0 
  normal = 1
  EFFlag = 0 
  name = ExitPort
  C = 0
  A = 0
}

Conductor
{
  j1 = Nx
  k1 = 0
  j2 = Nx
  k2 = Ny
  normal = -1
  EFFlag = 0 
  name = ExitPort
  C = 0
  A = 0
}

}