At high temperatures

the breakdown strength and energy storage density of polymers will drop sharply

which significantly limits the further development of polymer-based dielectric capacitors. The accumulation of space charges at high temperatures is a crucial factor causing electric field distortion in polymer insulation

posing a threat to its breakdown strength and energy storage density. In this paper

the PEA (pulsed electro-acoustic) testing device and break-down testing platform were improved

enabling tests at temperatures up to 200 ℃. The space charge distribution of polytetrafluoroethylene (PTFE) was measured at temperatures ranging from 90 to 180 ℃

and its AC (alternating current) and DC (direct current) breakdown characteristics were investigated from 25 to 180 ℃. The influences of high temperatures on the space charge characteristics and breakdown properties of the polymer were studied. The research reveals that PTFE exhibits no significant charge injection below 150 ℃. Above 150 ℃

a substantial number of positive charges are injected from the anode and migrate to the cathode in the form of space charge packets. Charge accumulation in PTFE induces significant electric field distortion within the material

reaching up to 1.8 times the original field intensity. The DC breakdown strength of PTFE exhibits a non-monotonic temperature dependence

initially increasing and then decreasing with rising temperature. In contrast

the AC breakdown strength shows a continuous downward trend over the same temperature range

with the DC degradation being more pronounced. The significant reduction in breakdown field strength of PTFE at high temperatures and under DC conditions is attributed to electric field distortion caused by the accumulation and migration of space charge packets within the material.