Coolidge x-ray tube.

                                           This new x-ray tube was designed by sir Coolidge in 1913. It was recognized as far superior to the Crooke’s tube. The Coolidge x-ray tube was vacuum tube, that allowed x-ray intensity and energy to be selected separately and great accuracy .

                    the Coolidge x-ray tube worked by thermionic emission principle. It was also known as hot cathode or electron tube. This was fully evacuated x-ray tube so there is no needed to production of x-ray to ionization. The filament used in tungsten. The cathode and anode are placed opposite to the cathode as like Crooke’s tube.

                                    when the high voltage is applied between the cathode and the anode. The filament get heated and the electrons are emitted, that electrons are traveling from cathode to anode. 99% of photons energy conversion in to heat and only 1% of photons energy produced x-ray.