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Manuscript Title: CASTOR 2: a two-dimensional laser target code.
Authors: J.P. Christiansen, N.K. Winsor
Program title: CASTOR 2
Catalogue identifier: ABUY_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 17(1979)397
Programming language: Fortran.
Computer: ICL 4/70.
Operating system: ICL MULTIJOB.
RAM: 110K words
Word size: 32
Keywords: Plasma physics, Thermonuclear fusion, Laser fusion, Lasers, Laser target, Two-dimensional Diffusion, Implicit, Iccg, Ionisation, Flux corrected transport, Rezoning, Laser physics, Inertial confinement.
Classification: 15, 19.7.

Subprograms used:
Cat Id Title Reference
ABUF_v1_0 OLYMPUS CPC 7(1974)245
ABUF_v2_0 OLYMPUS FOR IBM 370/165 CPC 9(1975)51
ABUF_v3_0 OLYMPUS FOR CDC 6500 CPC 10(1975)167
ABUV_v1_0 TRIP 1 CPC 16(1978)129

Revision history:
Type Tit le Reference
correction 000A CORRECTION 10/03/81 See below

Nature of problem:
The purpose of CASTOR 2 is to calculate the behaviour of laser- irradiated targets of moderate to high atomic Z. A two-dimensional MHD model in cylinder (r,z) geometry including three temperatures, time- dependent atomic physics, hydrodynamics and radiation transport- emission, is used in CASTOR 2. The code is meant to serve as a framework for further studies of laser targets either through manipulation of the existing physics and parameters or via extensions to both.

Solution method:
The target is described by 8 main variables which are functions of time t and the two spatial coordinates r and z. The solution is split into two stages. In stage I (diffusion stage) magnetic source terms to the diffusion equations are treated by the ADI method while the diffusion of the three temperatures and the magnetic field is done by either a splitting method or the ICCG method. In stage II (hydrodynamics) the hydrodynamic motion is solved by the FCT algorithms of Boris and Book.

Restrictions:
Version 2 of CASTOR which supersedes an unpublished version 1 provides a framework for laser target calculations. Because of the complexity of the physics included in the model there is no guarantee that any calculation can be completed by the code. It may therefore be necessary to "trim" calculations as explained in file INTRO of the code listing. The basic operation of the code follows the OLYMPUS pattern. Double precision should be used on computers with only 32 bits per word. The code conserves energy exactly so that error I displayed by the diagnostics should remain at round-off level. This provides a useful check against errors arising from modifications to the code. The accuracy of the calculation is highly sensitive to the precision level used (i.e. no. of bits per word) and two parameters RNDOFF and DELTA control the accuracy. The accuracy also depends on the number of meshpoints used as well as the timestep control settings.

Running time:
Execution times depend on the amount of physics included and on the number of meshpoints used. The execution times given below are obtained on the Culham Laboratory ICL 4/70 for the CASTOR 2 code with a mesh of 10 by 40, running in modes of increased complexity and these times are expressed in seconds per timestep. Because of the complexity of the physics these figures are only for guidance since convergence control, timestep control etc., may decrease or increase the execution time in a particular calculation.
                                      
 --------------------------------------------------------                
 1      1-temperature, diffusion by splitting,      3.5                  
        no hydrodynamics                                                 
 2      2-temperatures, diffusion by ICCG,          8.8                  
        no hydrodynamics                                                 
 3      3-temperatures, diffusion by splitting,    10.5                  
        no hydrodynamics                                                 
 4      2-temperatures and magnetic field,         18.0                  
        diffusion by ICCG, hydrodynamics                                 
 5      3-temperatures, ICCG, hydrodynamics,       25.0                  
        magnetic field, smoothing                                        
 --------------------------------------------------------                

CORRECTION SUMMARY
Manuscript Title: CASTOR 2: a two-dimensional laser target code. (C.P.C. 17(1979)397).
Authors: J.P. Christiansen, N.K. Winsor
Program title: 000A CORRECTION 10/03/81
Catalogue identifier: ABUY_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 23(1981)109
Classification: 15, 19.7.