1. NAME AND TITLE

EDNA: Electron Dose and Number Analysis Code by Kernel Integration.

This code package is retained by RSIC to preserve the space technology developed in the 1960s.

2. CONTRIBUTOR

Space Sciences Laboratory, NASA George C. Marshall Space Flight Center, Huntsville, Alabama.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; IBM 7090 and 7094.

4. NATURE OF PROBLEM SOLVED

The electron number flux and energy flux deposition rates are calculated as a function of depth in an aluminum slab. The impinging electron source can be normally incident or have either an isotropic or cosine angular distribution with respect to current. The energy spectrum of the incident electrons is arbitrary but is assumed to vary as Ae-BE between input data values.

5. METHOD OF SOLUTION

The electron energy flux deposition rate at depth z in an aluminum slab is computed by integrating, over energy, the product of the incident energy flux spectrum and the probability density for energy flux deposition at that depth. The integration is performed by evaluating the integrand at the midpoint of each integration step, multiplying by the step width, and summing the result. For this evaluation, the incident spectrum is assumed to vary as Ae-BE between input data points. The probability densities for energy flux depositions which are used in EDNA are those given in Ref. 1. These were derived from analyses of Monte Carlo results by Berger and Seltzer, for electron transmission and reflection factors. They are in the form of analytic expressions. The coefficients for the expressions are given in Ref. 1, and the user must provide appropriate values for these as input to EDNA.

An analagous treatment is used for computing the electron number flux deposition rate.

The energy range may be divided into several intervals, each with a different number of integration steps. The energy spectrum of incident particles is specified in input by a set of input energy and flux values.

6. RESTRICTIONS OR LIMITATIONS

Some dimensional limitations are as follows:

Maximum number of values describing incident spectrum: 40

Maximum number of energy intervals for which a different number of integration steps is provided: 10

7. TYPICAL RUNNING TIME

Estimated running time of the packaged sample problem: 1 minute.

8. COMPUTER HARDWARE REQUIREMENTS

The code was designed for the IBM 1130. It is also operable on the IBM 7090 with standard I-O units.

9. COMPUTER SOFTWARE REQUIREMENTS

The code is operable on the IBM-7090/7094 IBSYS Operating System using IBJOB

10. REFERENCES

C. E. Wuller, Jr., "Electron Transport from a Cosine Law Source," IN-SSL-N-68-13, Internal Note at Marshall Space Flight Center, Huntsville, Alabama (September 1968).

M. O. Burrell, J. J. Wright, and J. W. Watts, Jr., "The Calculation of Electron and Bremsstrahlung Dose Rates," Protection Against Space Radiation, NASA SP-169, p. 529 (1968).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source code and input and output for a sample problem.

12. DATE OF ABSTRACT

May 1969; updated April 1981, February 1985.

KEYWORDS: SPACE RADIATION; ELECTRON; KERNEL; SLAB