Krypton gives off a bright red-orange light when an electrical current is passed through it. This light is used to illuminate airfields, because the light is visible over long distances and penetrates fog. Krypton is used with argon in fluorescent lights as a low-pressure filling gas that helps reduce power consumption. To control filament evaporation, krypton gas is used in incandescent bulbs. Flash lamps in high-speed photography use krypton. It is often the gas used in neon lights, not neon.
In specialized MRI machines, hyperpolarized krypton-83 is used as a contrasting agent to image the airways of lungs. Hyperpolarized krypton-83 allows for the distinction between hydrophobic (to repel, not absorb or mix well with water) and hydrophilic (attracted to or dissolve within water) surfaces. This specific MRI is used to detect tobacco smoke deposits in lungs. Studies of tobacco smoke deposition by hyperpolarized krypton-83 conducted by Colorado State University show a longitudinal reduction in hyperbolic krypton-83 by 95 percent when brought in contact with surfaces that had been exposed to cigarette smoke.
Krypton lasers are used in eye surgery to stop bleeding, prevent retinal hemorrhagic diseases and prevent degenerative disorders of the retina and choroid. Krypton lasers are also used in experiments conducted by King Faisal Specialist Hospital in Saudi Arabia to heal skin wounds. Krypton fluoride lasers are used to implode fusion pellets. Electrical energy is added to krypton gas to make it react with fluorine. The compound krypton fluoride (KrF) is formed in this excited state. Krypton fluoride lasers have low energy, short time duration yet high level of power.
Krypton is used in multi-paned windows to reduce heat loss. In sealed glass windows, krypton gas is inserted between the panes to minimize convection currents and reduce the transfer of heat from indoors to outdoors. While using argon is cheaper, the non-toxic, non-reactive and clear krypton has better thermal performance. Manufacturers will sometimes mix argon and krypton gases as a compromise between krypton's elevated price point and argon's inferior thermal protection
Krypton is used to manufacture quasi-homogeneous electromagnetic calorimeters. Calorimeters measures the rate and scale of heat or energy production in chemical reactions. Krypton based calorimeters are made with liquid krypton which was previously outlawed due to small contamination of natural krypton to radioactive isotope krypton-85. This radioactive decay was also a source of excess noise, but further experiments proved that liquid krypton calorimeters have an energy resolution that is comparable to crystal calorimeters.
In 1960, krypton was used to define the length of a meter. The international definition of a meter was 1,650,763.73 times the width of the red-orange line produced by heating krypton-86. The previous definition of a meter was a metal bar located in Paris made of a platinum-iridium alloy. Both definitions were replaced in 1983. The current definition of a meter is the distance light travels in a vacuum during 1/299,792,458 seconds using a cesium atomic clock.
Krypton gas is an experimental fuel for deep space ion engines. Ion plasma thrusters are used on satellites, and though the preferred fuel is xenon, other gases such as krypton can be used. Krypton has been cited as a possible replacement for xenon, because it is more abundant and costs less than xenon. The difference in performance between krypton and xenon is said to be negligible.
Krypton-85 is used to search for heart leaks. It is used to detect intracardiac left-to-right shunts. The krypton-85 test is a useful ancillary method for shunt detection. During the procedure, the patient hyperventilates a krypton-85 air mixture while blood is simultaneously being drawn from a catheter placed in a right-sided chamber of the heart and a needle placed in an artery. Krypton-85's sensitivity allows it to detect small intracardiac shunts not discovered by oxygen saturation tests.
A computed tomography (CT) machine takes geometric three-dimensional dissections of an object in a process called "windowing." In certain CT experiments, krypton is combined with xenon in computed tomography machines to measure regional pulmonary ventilation. Krypton provides a better contrast for scanning lungs, loses intensity at a slower rate and has no documented side effect when compared to xenon. Adding krypton to low-dose xenon reduces noise and adds sensitivity to the measurements.
Krypton is also used in pen-ray or pencil lamps for wavelength calibration of a spectrograph. A spectrograph separates incoming waves into different frequencies and records those frequencies. Pen-ray and pencil lamps are name thus because of their slender shape. These lamps are also used in other spectroscopic instruments like monochromators and spectral radiometers.