Abstract: The method of the present disclosure is a method for producing a porous polymer film including: irradiating a strip-shaped polymer film with an ion beam while moving the polymer film transversely to the ion beam, so as to form a polymer film that has collided with ions in the beam; and chemically etching the formed polymer film so as to form openings and/or through holes corresponding to tracks left by the colliding ions in the polymer film. The ion beam (11) with which the polymer film is irradiated is obtained by folding a tail of an original beam (51) inwardly toward a center of the original beam by nonlinear focusing. The original beam is composed of ions accelerated in a cyclotron and has a cross-sectional intensity distribution profile in which an intensity is maximum at the center of the original beam and continuously decreases from the center toward the tail of the original beam, and the profile is an intensity distribution profile in a cross section perpendicular to a direction of the original beam.

Abstract: The method of the present disclosure includes: (I) irradiating a polymer film (1) with an ion beam composed of ions (2) accelerated in a cyclotron so as to form a polymer film that has collided with the ions in the beam; and (II) chemically etching the polymer film formed in the irradiation (I) so as to form openings (4b) and/or through holes (4a) corresponding to tracks (3) left by the colliding ions in the polymer film. In the irradiation (I), a beam current value of the ion beam is detected upstream and/or downstream of the polymer film in a path of the ion beam, and an irradiation conditioning factor in the irradiation of the polymer film with the ion beam is controlled based on the detected beam current value so that the polymer film can be irradiated with the ions at a predetermined irradiation density. The method of the present disclosure is suitable for industrial production of porous polymer films.

Abstract: The method of the present disclosure is a method for producing a porous polymer film including: irradiating a strip-shaped polymer film with an ion beam while moving the polymer film transversely to the ion beam, so as to form a polymer film that has collided with ions in the beam; and chemically etching the formed polymer film so as to form openings and/or through holes corresponding to tracks left by the colliding ions in the polymer film. The ion beam (11) with which the polymer film is irradiated is obtained by folding a tail of an original beam (51) inwardly toward a center of the original beam by nonlinear focusing. The original beam is composed of ions accelerated in a cyclotron and has a cross-sectional intensity distribution profile in which an intensity is maximum at the center of the original beam and continuously decreases from the center toward the tail of the original beam, and the profile is an intensity distribution profile in a cross section perpendicular to a direction of the original beam.

Abstract: Disclosed is a method for producing a porous polymer film. This method includes the steps of: (I) irradiating a polymer film with an ion beam of accelerated ions so as to form a polymer film that has collided with the ions in the beam; and (II) chemically etching the polymer film formed in the step (I) so as to form openings and/or through holes corresponding to tracks of the colliding ions left in the polymer film. In the step (I), the polymer film is placed in an atmosphere with a pressure of 100 Pa or more, and the polymer film placed in the atmosphere is irradiated with the ion beam that has passed through a beam line maintained at a lower pressure than the pressure of the atmosphere and through a pressure barrier sheet disposed at an end of the beam line to separate the beam line from the atmosphere.