What is "Radiation Friction"? From this report on generating high intensity magnetic fields (emphasis added)

The Faraday effect has been known for a long time. It refers to the
  polarization plane of an electromagnetic wave propagating through a
  non-magnetic medium, which is rotating in the presence of a constant
  magnetic field. There is also an inverse process of the generation of
  a magnetic field during the propagation of a circularly polarized wave
  through a crystal or plasma. It was considered theoretically in the
  1960s by Soviet theorist Lew Pitaevsky, a famous representative of
  Landau's school. The stronger the wave, the higher the magnetic field
  it can generate when propagating through a medium. However, a
  peculiarity of the effect is that it requires absorption for its very
  existence—it does not occur in entirely transparent media. In highly
  intense electromagnetic fields, electrons become ultrarelativistic,
  which considerably reduces their collisions, suppressing conventional
  absorption. The researchers demonstrate that at very high laser wave
  intensities, the absorption can be effectively provided by radiation
  friction instead of binary collisions. This specific friction leads to
  the generation of a superstrong magnetic field.

 A: Radiation friction is where a charged particle like an electron emits say synchrotron radiation when you accelerate it. Conservation of energy means the electron loses energy, so you lose some of the energy you put in. It's not quite the same as real friction, but they call it radiation friction anyway.
You can see a reference to it in this physicsworld article covering the same paper: Radiation friction could make huge magnetic fields with lasers. 
A: Radiation friction is another name for radiation reaction, also known as the Abraham-Lorentz force. 

In the physics of electromagnetism, the Abraham–Lorentz force (also
  Lorentz–Abraham force) is the recoil force on an accelerating charged
  particle caused by the particle emitting electromagnetic radiation. It
  is also called the radiation reaction force or the self force.

From Wikipedia, Abraham-Lorentz force. The article goes into quite some detail with some good references.
This paper uses both "radiation reaction" and "radiation friction" to mean the same thing. I've only seen Italian scientists using "radiation friction" instead of the other names, so perhaps it's a more common term in the Italian physics community.
