Kebede, Legesse VV (PhD)Kedir, Mohammed2018-07-022023-11-092018-07-022023-11-092005-07http://10.90.10.223:4000/handle/123456789/5186Under the relativistic plasma diffusion theory (Kebede, 2002, 1996), we investigate the magnetic field evolution of millisecond pulsars beyond the X-ray death line by taking the competitive nature of magnetic field revival due to mass accretion and its decay due to one of the cooling sources called photon emission leading to pulsar field evolution at about threshold magnetic field for X-ray productions into account. Our study shows that the magnetic field is no more monotonous for old pulsars. This evolution of the magnetic field is applied to address the issue of the 35 day cycle of X-ray radiations of Hercules X-lenMagnetic Field EvolutionThesis