Cosmic-Ray Ionization Rate in Protoplanetary Disks with Sheared Magnetic Fields

We investigate the effects of magnetic field configurations on ionization rate by cosmic rays in protoplanetary disks. First, we consider cosmic-ray propagation from interstellar medium (ISM) to disks and showed that density around disk should be 2 times lower than ISM value. Then, compute attenuation The fields are stretched azimuthal directions, need detour while propagating midplane. Our results show detouring effectively enhances column about two orders magnitudes. employ a typical diffuse ISM, which is considered too high consistent with observations disks, find significantly shielded at In case IM Lup, midplane very low for $r\lesssim\,100$ au, value as large outer radii. recent ALMA observation indicates radial gradient rate. radii may activate magnetorotational instability was thought suppressed due ambipolar diffusion. These will have strong influence dynamical chemical evolutions