Other methods of X-ray production Long running debate, I would like to find a definitive answer.
In a long glass tube (borosilicate or other common glass) with high frequency AC excitation at one end, 50-60kV, with high evacuation, I see a pale green glow in the glass.  Some people claim this is due to X-ray production when the electrons collide with the glass.  Others claim this is "cathode rays" being produced.  My understanding of "Cathode rays" is that this is an old term for electrons moving through the vacuum. 
I have seen youtube videos showing increased counts on a radiation detector, but I know that this could be faked or due to other effects.
https://www.youtube.com/watch?v=af8wnm2eGWw
I've seen the classic description of how X-ray tubes work, but I am wondering if this is another method of generating X-rays, probably far less efficient than the metal target.
 A: Interesting video. Yes I'm pretty sure this is a method for generating X rays. In fact, before the invention of the Coolidge tube (incandescent tungsten cathode filament which allowed independent control of voltage and current) all X-ray tubes were a variant of this: they had a pointy cathode, a flat (stationary) anode, and a small amount of gas. When HV was applied (usually AC since that is easier to generate), the gas at the cathode tip would ionize, causing electrons to be accelerated to the anode. During the acceleration, the electrons would continue to ionize gas, and ions would start to flow to the cathode. These ions would bombard (heat) the cathode, increasing the electron emission further. Problem with this design: for a given value of HV and gas pressure, the current was "what it was". So the radiologist would put his hand in the beam to see if he got a good shadow on the phosphor screen. If not, then he would get out the Bunsen burner and heat a small amount of asbestos that was kept inside a small tube off the main bulb. The hot asbestos would out gas, and raise the pressure in the tube. Soon it would work at peak efficiency again...
You see similar things happening here. The metal rod at the top of the lamp acts as a capacitive ground - given the very high voltage, a tiny charge will flow from the tip of the filament to the rod. There is a small amount of gas in the tube which is ionized and gives rise to the light you see. The electrons eventually bombard the metal "anode" and produce Bremsstrahlung - note that without the metal, you were getting a glow and no reading on the Geiger counter. There is a similar demonstration online which is more convincing in its use of conventional materials, but which otherwise shows many of the same phenomena. 
It is almost certainly very inefficient. Most of the energy in an X-ray tube is converted to heat as the electrons burrow too deeply into the tungsten target for their radiation to escape- apart from the fact that only the most violent deceleration produces X-rays with high enough energy to penetrate the bulb and be detected.
I noticed that when the "alpha window" was removed, the reading in your video went up. Since there was also a biscuit tin and glass bulb in the way I suspect there was a lot more low energy radiation generated than was detected. Good stuff for skin cancer.
The experiment as shown should not be repeated. Not only were the HV precautions extremely poor, but so were the radiation safety precautions. Please don't try this at home...
A: There are two fundamental mechanisms for producing X-rays (for research and application)
(i) through transition of an electron in a high energy level to a lower one in an atom (mostly solid)
(ii) through acceleration of charged particles (mostly electrons)
X-ray tubes: In an X-ray tube both mechanisms are in action. High energy electrons hit to the surface of a metal. In the first couple of nanometers, some of the high energy electrons slow down (decelerate) and produce so called "bremsstrahlung" radiation (see hyperphysics page). Some of the high energy electrons kick out core electrons from the metal. The electrons in the metal fill the created core hole and emit photons.
Particle (electron) Accelerators: In a particle accelerator high energy electrons, travelling with speeds very close to speed of light, are accelerated through powerful magnets. Every time the trajectory of the electrons are bent electrons emit photons (see wikipedia page for a Synchrotron).
