1. Code Name FWR2D
2. Code Category: reflectometry simulation
3. Primary Developer Ernest Valeo
4. Other Developers and Users Gerrit Kramer, Raffi Nazikian, Eliot Feibush, UC Davis, POSTECH
5. Short description (one line if possible) Full wave simulation of reflectometry - 2 dimensional.
6. Computer Language (Fortran77, Fortran90, C, C++, etc) and approx # of lines. FORTRAN 90, approximately 20000 lines.
7. Type of input required (including files and/or output from other codes). Is there any special input preparation system (eg, GUI) The following input is required: antenna properties, plasma dielectric model, mesh geometry, wave solver numerical parameters, turbulent fluctuation data, output directives. The input is presented to the code in a combination of files (*.inp) with namelist data, a set of netcdf files containing plasma profile data, an ascii file containing complex Electric field patterns at the antenna plane, and a netcdf file containing random seeds to generate realizations of fluctuations in electron density. These files are generated in a number of ways. The plasma profile data can be generated analytically, or by reading TRANSP generated profile data. The antenna description is either analytically specified (antenna size, location, angle of incidence, focal length, etc.) or from a dataset generated by the CODE5 optics design code. The required .inp files can be generated manually, or interactively either through the ELFRESCO GUI (Eliot Feibush) or by a preprocessor (Gerrit Kramer).
8. Type of output produced (including files that are read by other codes and sizes of large files and synthetic diagnostics) Wave fields, plasma dielectric, fluctuation spectral profiles, ..., are output into one or more netcdf files.
9. Describe any postprocessors which read the output files. A number of Yorick scripts have been written to analyze the output.
10. Status and location of code input/output documentation. The developer's running commentary is contained in a NOTES.txt file in the source tree.
11. Code web site? No.
12. Is code under version control? What system? Is automated regression testing performed? The code is maintained within CVS. No automated regression testing is performed.
13. One to two paragraph description of equations solved and functionality including what discretizations are used in space and time: The objective is to simulated microwave reflectometry in which a mm wavelength electromagnetic wave is launched external to the plasma, propagates to a reflecting surface and back out of the plasma. The time series of the phase and amplitude patterns at the receiving antenna(e) are used to infer spectral characteristics of the plasma micro-turbulence (on wavelengths somewhat longer than the probing wavelength). A large ensemble of wave propagation simulations (several hundred) are typically necessary to generate sufficiently good statistical data to infer spectral properties. An efficient solver is demanded for acceptable throughput. In order to achieve this, the simulation has been decomposed into domains. The incoming radiation is tracked from the boundary to near the reflection layer within the paraxial approximation. The paraxial field amplitudes are prescribed as input to a full wave, implicit time-dependent solver in the domain surrounding the reflection surface. The steady-state solution is obtained. The reflected field is initial data for the outgoing paraxial beam which is advanced to determine the outgoing field at the plasma edge . A vacuum Green's function transfers the pattern to the plane of the receiving antenna.
14. What modes of operation of code are there (eg: linear, nonlinear, reduced models, etc ) The code solves the linear wave equation for either, cold, warm or mildly relativistic plasma dielectric models.
15. Journal references describing code "Two-dimensional simulations of correlation reflectometry in fusion plasmas," E. J. Valeo, G. J. Kramer and R. Nazikian, Plasma Phys. Control. Fusion 44 L1, (2002).
16. Codes it is similar to and differences (public version)
17. Results of code verification and convergence studies (with references)
18. Present and recent applications and validation exercises (with references as available) "Simulation of optical and synthetic imaging using microwave reflectometry," G. J. Kramer, R. Nazikian and E. J. Valeo, Plasma Phys. Control. Fusion 46 695, (2004); "2D reflectometer modeling for optimizing the ITER low-field side X-mode reflectometer system," G. J. Kramer, R. Nazikian, E. J. Valeo, R. V. Budny, C. Kessel and D. Johnson, Nucl. Fusion 46 5486 (2006); "Measurement of Turbulence Decorrelation during Transport Barrier Evolution in a High-Temperature Fusion Plasma," R. Nazikian, etal, Phys. Rev. Lett. 94, 135002 (2005).
19. Limitations of code parameter regime (dimensionless parameters accessible) Weakly converging / diverging microwave beam.
20. What third party software is used? (eg. Meshing software, PETSc, ...) netcdf, NAG
21. Description of scalability An early version of the code was parallelized. This functionality no longer exists. Typically, multiple instances are run concurrently in order to accumulate the required statistical properties of the reflected radiation.
22. Major serial and parallel bottlenecks.
23. Are there smaller codes contained in the larger code? Describe. The code is modular. The paraxial and full wave solvers can be invoked separately.
24. Supported platforms and portability Should work on any unix system with netcdf and NAG libraries available.
25. Illustrations of time-to-solution on different platforms and for different complexity of physics, if applicable.