A modified orbital motion limited (OML) theory
  The validity of the orbital motion limited (OML) theory is reviewed with reference to the floating potential acquired by a spherical object immersed in a plasma. A new and perhaps more realistic approach for obtaining the floating potential is introduced by including the current outward from the spherical object and the current coming from infinity. This novel approach is also valid for cases where the standard OML theory ceases to apply. 
Zahida Ehsan, Nodar L. Tsintsadze, and S. Poedts
physics.plasm-ph