#Parmela code code#
#Parmela code series#

The energy change through the time step is calculated from expressions derived from the LiГ©nardвЂ“Wiechart formulae, and from this energy change the particle's momentum is updated. For the CSR calculations, the macro-particles are further combined into macro-particle-bins that follow the central trajectory of the bend. At each time step through the calculation, the momentum of each particle is updated due to the presence of external and self-fields.

#Parmela code series#

An electron bunch is simulated by a collection of macro-particles, which traverses a series of beam line elements. To that end, we have developed a new version of PARMELA, named PARMELA_B and written in Fortran 95, which includes a coherent synchrotron radiation (CSR) routine and an improved, generalized space charge (SC) routine. The current generation of beam transport codes which were developed for high-energy, low-charge beams with low self-fields are inadequate to address this energy and charge regime, and better computational tools are required to accurately calculate self-fields. Recent interest in advanced laser light sources has stimulated development of accelerator systems of intermediate beam energy, 100вЂ“200В MeV, and high charge, 1вЂ“10В nC, for high power FEL applications and high energy, 1вЂ“2В GeV, high charge, SASE-FEL applications. The results from the calculations for the chicane buncher of the 1 kW visible FEL line at Boeing, indicate that the old circular algorithm of the SCHEFF subroutine A dynamic meshing routine has been added to allow good resolution for pulses that undergo significant changes in their longitudinal or transverse dimensions.

#Parmela code code#

The Boeing version of the PARMELA code has been modified to compute more correctly the space charge effects for electron pulses with highly elliptical transverse cross-sections. With an energy slew of в€’510 keV/cm, the electron Summary and conclusion The chicane buncher operates at about 20 MeV, where the three-dipole bending magnets (shaded regions) have field strength of 1340 G. We will report here only on the calculations for the buncher of the Boeing visible FEL beam line. Several test runs have been made to evaluate the differences arising from using the new elliptical algorithm versus the old circular algorithm. The modifications have been made to this section and related Comparison of circular and elliptical algorithms A detailed description of the method can be found in Ref. The PARMELA SCHEFF subroutine calculates the space charge impulse applied to a macro-particle at each time step. Modifications have been made to PARMELA to enhance its ability to model electron bunches which, through the course of traversing various beam line elements such as the bends and quadrupoles, can become greatly elongated in the cross sectional plane ( x, y). PARMELA with the old version of SCHEFF consistently overestimates the emittance increase in the buncher by approximately 30вЂ“40%. Section 3 presents test runs showing the differences between results produced by the old (circular) and new (elliptical) algorithms in the SCHEFF subroutine. The modifications are described in Section 2. A dynamic grid has been added to improve resolution as the pulse evolves in time. These changes are more general than those presented in Ref. Modifications have been made to PARMELA to allow modeling pulses of elliptical cross section. This is strongly violated in the buncher of the 1 kW visible FEL beam line currently under construction at The Boeing Company in Seattle. One critical assumption in PARMELA is that the electron pulse cross-section is nearly circular through the beam line. The LANL-developed PARMELA code is a very useful, computationally efficient tool for electron beam line design, but it relies upon simplifying assumptions.