Hi Ren,
I'd hope Darby sees this thread and chimes in with anything I might be stating incorrectly in what follows, but I'll take a shot.
Can anyone explain if the speed of the electron orbit of an atom increases or decreases when the atom is in motion?
That's a pretty deep question, and one that would he hard to answer without asking some more questions about what you specifically mean. And even then, there is the question of whether the electron is a particle orbiting the nucleus, as told by the Bohr model. The quantum model says the electron is a probability cloud, and in such a model one does not even make the assumption that the electron is moving as a particle. It could just be disappearing and reappearing at a different spot in the electron cloud.
Second, I assume you mean in your question the speed of the electron with respect to some neutral (inertial) reference frame, and not with respect to the atom's nucleus. In this case, and assuming the Bohr model of an orbiting electron is correct, then the inertial speed (meaning the magnitude of the total velocity vector) would modulate as the atom moved. The speed of the atom itself (if it was constant) would be like a DC term. The additive speed of the electron would be like an AC signal component on top of the atom's linear, constant velocity (the DC component). This is a simple dynamic relationship that could easily be modeled in a program like MATLAB. An analogy would be modeling the forward motion of a helicopter while also modeling the rotation of its blades. The heli forward motion is a DC velocity, with the rotating blades being an AC additive.
Such as accelerating through a particle accelerator?
OK, in this case I do not believe you are accelerating entire atoms, but rather electrons that have been stripped off of atoms.
Or is electron orbit speed even measureable at that degree? Any degree?
As indicated above, quantum theory is based on the claim that the simple Bohr model of the electron, whizzing around the nucleus in a nice, stable orbit is incorrect. In quantum theory, the electron is not a particle, but it is a probabilistic wave function. Quite literally one could claim that the electron is not so much moving in an arc around the nucleus but instead appearing and disappearing in various different places... with the wave function denoting the possibilities that the electron appears in certain places more often than in other places.
Here is a good article, with some great graphics, that might help.
http://www.blazelabs.com/f-p-flaw.asp
RMT