1. Code Name: WKB

2. Category: XIIIa. Utility: Math/Physics

3. Responsible Physicist: R. B. White

4. Others involved in code development: None

5. One line description: Solution of differential equations using WKB

6. Computer systems which code runs on: Cray

7. Typical running time: Various

8. Approximate number of code lines: ~ 500

9. Does this code read data files from another code? No.

10. Does this code produce data files that can be read by another code? No.

11. 1-2 paragraph description of code: Interactive solution of differential equations using Stokes plots and iterative approach to eigenvalues.

12. Similar codes to this code, and distinguishing differences: None.

13. Journal References describing code: R. B. White, J. of Comput. Phys. 31 409 (1979).

14. New code capabilities planned for next 1-2 years: None.

15. Code users: W. Tang, L. Chen, P. Kaw, R. Dewar, T. W. Johnston, Ed Williams, Al Simon et al.

16. Present and recent applications of code: Various

17. Status of code input/output documentation. Check one: (X) does not exist ( ) incomplete ( ) exists

18. Year Code was first used and present frequency of use: 1978, every few months

19. Estimate of Man-Years invested in developing code: 1

20. Catagories of usage of Code: (x ) application code to do analysis and prediction of experiments (x ) numerical testbed of theoretical ideas ( ) physics module to be used in integrated moddelling ( ) code for machine design

21. Language code is writen in: fortran

22. Results of intercomparisons with other codes and results of validation against experiments. Theory of Universal Eigenmodes in a Sheared Magnetic Field L. Chen, P. N. Guzdar, R. B. White, P. K. Kaw, and C. R. Oberman Phys. Rev. Lett. , 649-653 (August 1978) Impurity Effects on Ion-Drift-Wave Eigenmodes in a Sheared Magnetic Field W. M. Tang, R. B. White, and P. N. Guzdar Phys. Fluids , 167-173 (January 1980)