NOVELTY - Producing high pressure polyethylene, comprises: contacting first amounts of ethylene, a polar comonomer and one or more 3-12C unsaturated modifiers in the presence of a first amount of initiator in a reaction system at sufficient reaction conditions; removing at least a portion of a purge gas from purge gas recycle stream; removing at least a portion of the unreacted polar comonomer from the comonomer recycle stream; and continuing the reaction in the reaction system by contacting second portions of ethylene, polar comonomer and the unsaturated modifiers.    USE - The process is useful for producing high pressure polyethylene (claimed), which is useful for fabricating photovoltaic modules.    ADVANTAGE - The process provides high pressure polyethylene with improved crosslinkability without any appreciable, i.e. negligible, change in melt index and vinyl acetate content. The high pressure polyethylene improves: structural stability and protects against mechanical impacts, chemical attack or environmental impact of the photovoltaic cell; final property of the photovoltaic cell, thus reducing process and cycle times for fabricating photovoltaic modules; and chemical, weather and wear resistances of the photovoltaic cell.    DETAILED DESCRIPTION - Producing high pressure polyethylene, comprises: (a) contacting first amounts of ethylene, a polar comonomer and one or more 3-12C unsaturated modifiers in the presence of a first amount of initiator in a reaction system at sufficient reaction conditions, where a reaction system effluent comprises the polyethylene resin, a comonomer recycle stream comprising unreacted polar comonomer, and purge gas recycle stream comprising purge gas; (b) removing at least a portion of the purge gas from purge gas recycle stream; (c) removing at least a portion of the unreacted polar comonomer from the comonomer recycle stream; and (d) continuing the reaction in the reaction system by contacting second portions of ethylene, polar comonomer and the unsaturated modifiers. INDEPENDENT CLAIMS are included for:    (1) a process-1 for increasing the crosslinkability of the high pressure polyethylene, comprising the steps (a)-(d) as above per se, where the polyethylene resin has a melt index of 0.1 g/10 minute to 500 decigram/minute; and    (2) a copolymer produced in a high pressure polymerization process, comprising at least 50 wt.% of ethylene, at least 20 wt.% of polar comonomer, and 0.4-4 wt.% of units derived from the unsaturated modifier, where the copolymer has a melt index as measured according to ASTM D1238 (2.16 kg, 190 degrees C), of 0.15-0.50x 102 decigram/minute and a crosslink index (MH-ML) of at least 2.