Does Bremsstrahlung refer to the radiation produced exclusively by deceleration? A charged particle, decelerated by the electric field of another charged particle, typically an atomic nucleus, emits electromagnetic radiation, called Bremsstrahlung. This process typically happens in the matter in the presence of electric fields of the atomic nuclei in the medium.
Question The term Bremsstrahlung literally means braking radiation or deceleration radiation. But instead of being decelerated, if the charged particle is accelerated by a nucleus, will the emitted radiation be qualitatively or quantitatively any different than in the case of deceleration? From the physics point of view, is there any importance of using the word 'deceleration' in defining Bremsstrahlung?
 A: For one, it's important to note that the distinction between acceleration and deceleration is not a relativistic invariant, so the question does not make sense in absolute terms.
That said, I'm not aware of any experiment where electron speed-up (as observed in the laboratory frame) causes detectable emission of bremsstrahlung.
However, it's also crucial to keep in mind that acceleration is a vector quantity and it need not be parallel to the velocity, and particularly in circular motion you can have constant speed while subject to large accelerations. This is the basis for synchrotron radiation, which is a type of bremsstrahlung and is of huge technological importance.
A: Bremsstrahlung is done by high voltage source  which works as electron gun and when electrons hit the metal surface a wave with certain wavelength will be radiated (only considering a narrow range) which is done specifically by certain metals that allow the radiation of necessary wavelength. On the other hand accelerating electron also emits electromagnetic waves but to simplify and build the machinery fast and simple the method of declaration is used where Bremsstrahlung clearly refers to the methodology itself so, yes the term deceleration is necessary.
