------------------ TED readme ----------------------------------------- /* DESCRIPTION OF TED (Thermal Electron Energy Distribution) Brief Description The TED instrument provides energy distribution of thermal electrons in the energy range of 0 to 5 eV in reference to the DC offset bias (-3.5 to -0.5 volt) from the spacecraft potential. The energy range from 0 to 5 eV is divided into 32 steps, equally spaced on a linear scale. Output signal level (Iout) recorded in each file means the second harmonic component of incident electron current to the TED probe. The relationship between Iout (ranges from 0 to 255) and the energy distribution function, f(E), is expressed by the folowing equation : f(E) = 1.53*10**3 * 10**((Iout-81.6)/51.0) * SQRT( E ) Unit : [/eV cm**3] where E denotes the probe potential (Ep) with reference to the space potential (E0), i.e., Ep-E0. The relationship between accutual probe potential and the Energy-Step (1-32, in the data file) can be expressed by the folllowing equation : E = 5.0/32.0 * (Energy-Step) Regarding how to define a space potential from data, please refer to the paper listed below. Please contact the following person or refer to the paper by Abe et al. (1990) for detailed information. PI : K. Oyama, Institute of Space and Astronautical Science, Yoshinodai, Sagamihara, Kanagawa 229, JAPAN TEL: +81-427-51-3911 ext.2524 FAX: +81-427-59-4237 E-Mail: oyama@bochan.ted.isas.ac.jp Takumi Abe College of Science and Engineering Aoyama Gakuin University 6-16-1, Chitosedai, Setagaya-ku, Tokyo 157, JAPAN TEL: +81-3-5384-1111 ext.3422 FAX: +81-3-5384-1121 E-Mail: abe@ee.aoyama.ac.jp Reference Abe, T., K. Oyama, H. Amemiya, S. Watanabe, T. Okuzawa, and K. Schlegel, Measurements of Temperature and Velocity Distribution of Thermal Electrons by Akebono (EXOS-D) Satellite, J. Geomag. Geoelectr., 42, 537-554, 1990. */ Sample Program to read TED data file #include #include #include main() { FILE *filein, *filout; static char filnm1[17], ymdtim[12], chzero ; static char filnm2[] = "output.data" ; char iymd[6], itim[6] ; int i,j, n1,n2, cdata ; int jfe[15][32], jtmp[15], itmp1, itmp2 ; long timcal(); long itime, c; filout = fopen(filnm2,"w"); while(scanf("%s",filnm1) != EOF) { strcat(filnm1,".ted"); filein = fopen(filnm1,"rb"); printf(" file name : %s\n",filnm1); for (i=0; i<=5; i++) { iymd[i] = getc(filein); putc(iymd[i],filout); } for (i=0; i<=5; i++) { itim[i] = getc(filein); putc(itim[i],filout); } itime = atoi(itim) ; for (i=0;i<=499;i++) { cdata = getc(filein); } fprintf(filout,"\n",itime); while( (n1 = getc(filein)) != EOF ) { n2 = getc(filein) ; for(i=0 ; i<=14 ; i++) { c = timcal(itime,n1,i) ; itmp1 = getc(filein) ; itmp2 = getc(filein) ; jtmp[i] = itmp1*256 + itmp2 ; fprintf(filout,"%7d%6d",c,jtmp[i]) ; for(j=0 ; j<=31 ; j++) { jfe[i][j] = getc(filein); } for(j=0 ; j<=31 ; j++) { fprintf(filout,"%3d",jfe[i][j]) ; } fprintf(filout,"\n",itime); } } fclose(filein) ; } fclose(filout) ; } long timcal(itime,n1,i) int n1, i ; long itime ; { long int isec, jsec, ksec, jhour, jmini, jseco ; long int c ; isec = 120*n1 + 8*i ; jsec = 3600*(itime/10000)+60*((itime%10000)/100)+(itime%100) ; ksec = isec+jsec ; jhour = ksec/3600 ; jmini = (ksec-3600*jhour)/60 ; jseco = ksec-3600*jhour-60*jmini ; c = jhour*10000 + jmini*100 + jseco ; return(c); }