Method and device for stabilizing precursor fibers or films for producing carbon fibers or films

A method for stabilizing precursor fibers for the production of carbon fibers, comprising the steps of:

• continuously introducing, passing and removing the precursor fibers into, through and from a process chamber;
• setting a predetermined process gas atmosphere different in composition from ambient air in said process chamber, said process gas atmosphere being below atmospheric pressure and containing air and/or pure oxygen as a reactive component and/or catalyst, the air and/or pure oxygen having a predetermined partial pressure;
• while the precursor fibers are in the process chamber, heating the precursor fibers to at least a first temperature and maintaining the first temperature for a predetermined period of time, wherein the method is free from steps in which magnetic fields are applied to the precursor fibers in the process chamber.