PROCEDURE: load_i8_pla PURPOSE: loads IMP-8 Plasma Experiment key parameter data for "tplot". INPUTS: none, but will call "timespan" if time range is not already set. KEYWORDS: TIME_RANGE: 2 element vector specifying the time range DATA: returns data structure RESTRICTIONS: This routine expects to find the master file: 'i8_k0_pla_files' In the directory specified by the environment variable: 'CDF_DATA_DIR' See "make_cdf_index" for more info. SEE ALSO: "make_cdf_index","loadcdf","loadcdfstr","loadallcdf" CREATED BY: Davin Larson FILE: load_i8_pla.pro LAST MODIFICATION: 02/04/12