Editing Cold cathode (section)

===Effects of internal heating===
In systems using [[alternating current]] but without separate [[anode]] structures, the electrodes alternate as anodes and cathodes, and the impinging electrons can cause substantial localized heating, often to [[red heat]]. The electrode may take advantage of this heating to facilitate the thermionic emission of electrons when it is acting as a cathode. (''Instant-start'' fluorescent lamps employ this aspect; they start as cold-cathode devices, but soon localized heating of the fine [[tungsten]]-wire cathodes causes them to operate in the same mode as [[hot-cathode]] lamps.)

This aspect is problematic in the case of backlights used for [[liquid-crystal display|LCD]] TV displays. New energy-efficiency regulations being proposed in many countries will require variable backlighting; variable backlighting also improves the perceived contrast range, which is desirable for LCD TV sets. However, CCFLs are strictly limited in the degree to which they can be dimmed, both because a lower plasma current will lower the temperature of the cathode, causing erratic operation, and because running the cathode at too low a temperature drastically shortens the life of the lamps.{{citation needed|date=November 2015}} Much research is being directed to this problem, but high-end manufacturers are now turning to high-efficiency white [[LED]]s as a better solution.{{citation needed|date=December 2021}}