LED ESL » Plasma lamp

Producers of plasma lamp

LED — Thu, 10 Dec 2009 05:45:20 +0000

Companies producing or developing plasma lamps include Ceravision, Luxim and Topanga Technologies.

Luxim’s LIFI, or light fidelity lamp, claims 120 lumens per RF watt (ie before taking into account electrical losses). The lamp has been used in Robe lighting’s ROBIN 300 Plasma Spot moving headlight. It was also used in a line of, now discontinued, Panasonic rear projection TV.

Ceravision has introduced a combined lamp and luminaire under the trade name Alvara for use in high bay and street lighting applications. It uses an optically clear quartz waveguide with an integral burner allowing all the light from the plasma to be collected. The small source also allows the luminaire to utilize more than 90% of the available light compared with 55% for typical high-intensity discharge fittings. Ceravision claims the highest luminaire efficacy rating of any light fitting on the market and to have created the first HEP lamp. Ceravision uses a magnetron to generate the required RF power and claim a life of 20,000 hours.

High-efficiency plasma (HEP)

LED — Thu, 10 Dec 2009 05:43:55 +0000

High-efficiency plasma lighting is the class of plasma lamps that have system efficiencies of 90 lumens per watt or more. Lamps in this class are potentially the most energy efficient light source for outdoor, commercial and industrial lighting. This is due not only to their high system efficiency but also to the small light source they present enabling very high luminaire efficiency.

Luminaire Efficacy Rating (LER) is the single figure of merit the National Electrical Manufacturers Association have defined to help address problems with lighting manufacturers’ efficiency claims and is designed to allow robust comparison between lighting types. It is given by the product of luminaire efficiency (EFF) times total rated lamp output in lumens (TLL) times ballast factor (BF), divided by the input power in watts (IP):

LER = EFF × TLL × BF / IP

The “system efficiency” for a High Efficiency Plasma lamp is given by the last three variables, that is it excludes the luminaire efficiency. Though plasma lamps do not have a ballast they have an RF power supply that fulfils the equivalent function. In electrodeless lamps the inclusion of the electrical losses or “ballast factor” in lumens per watt claimed can be particularly significant as conversion of electrical power to radio frequency (RF) power can be a highly inefficient process.

Many modern plasma lamps, such as those manufactured by Ceravision and Luxim have very small light sources—far smaller than HID bulbs or fluorescent tubes—leading to much higher luminaire efficiencies also. High intensity discharge lamps have typical luminaire efficiencies of 55% and fluorescent lamps of 70%. Plasma lamps typically have luminaire efficiencies exceeding 90%.

Heat and power of Plasma Lamp

LED — Thu, 10 Dec 2009 05:43:23 +0000

The use of a high dielectric waveguide allowed the sustaining of plasmas at much lower powers – down to 100W in some instances. It also allowed the use of conventional gas-discharge lamp fill materials which removed the need to spin the bulb. The only issue with the ceramic waveguide was that much of the light generated by the plasma was trapped inside the opaque ceramic waveguide. In 2009 Ceravision introduced an optically clear quartz waveguide which appears to resolve this issue.

Plasma Lamp Size

LED — Thu, 10 Dec 2009 05:42:51 +0000

Around 2000 a system was developed that concentrated radio frequency waves into a solid dielectric waveguide made of ceramic which energized a light emitting plasma in a bulb positioned inside. This system, for the first time, permitted an extremely compact yet bright electrodeless lamp. The invention has been a matter of dispute. Claimed by Frederick Espiau (then of Luxim now of Topanga Technologies), Chandrashekhar Joshi and Yian Chang, these claims were disputed by Ceravision Limited. Recently a number of the core patents have been assigned to Ceravision

Limited life of plasma lamp

LED — Thu, 10 Dec 2009 05:42:08 +0000

In the past, the life of the plasma lamps was limited by the magnetron used to generate the microwaves. Solid state RF chips can be used and give long lives. However, using solid state chips to generate RF is currently an order of magnitude more expensive than using a magnetron and so only appropriate for high value lighting niches. It has recently been shown by Dipolar of Sweden to be possible to greatly extend the life of magnetrons to over 40,000 hours making low cost plasma lamps possible.

Plasma Lamp Description

LED — Thu, 10 Dec 2009 05:41:23 +0000

Modern plasma lamps are a family of light sources that generate light by exciting a plasma inside a closed transparent burner or bulb using radio frequency (RF) power. Typically, such lamps use a noble gas or a mixture of these gases and additional materials such as metal halides, sodium, mercury or sulfur. In modern plasma lamps a waveguide is used to constrain and focus the electrical field into the plasma. In operation the gas is ionized and free electrons, accelerated by the electrical field collide with gas and metal atoms. Some electrons circling around the gas and metal atoms are excited by these collisions, bringing them to a higher energy state. When the electron falls back to its original state, it emits a photon, resulting in visible light or ultraviolet radiation depending on the fill materials.

The first commercial plasma lamp was an ultraviolet curing lamp with a bulb filled with argon and mercury vapor developed by Fusion UV. That lamp led Fusion Lighting to the development of the sulfur lamp, a bulb filled with argon and sulfur which is bombarded with microwaves through a hollow waveguide. The bulb had to be spun rapidly to prevent it burning through. Fusion Lighting did not prosper commercially, but other manufacturers such as LG Group continue to pursue sulfur lamps. Sulfur lamps, though relatively efficient have had a number of problems, chiefly:

Limited life – magnetrons had limited lives
Large size
Heat – the sulfur burnt through the bulb wall unless they were rotated rapidly
Low power – they could not sustain a plasma in powers under 1000W

What is Plasma lamp?

LED — Thu, 10 Dec 2009 05:40:14 +0000

Plasma lamps are a relatively new (as of 2009^[update]) type of highly efficient electrodeless lamp energized by radio frequency (RF) power. They are distinct from the novelty plasma lamps that were popular in the 1980s.

The electrode-less lamp was invented by Nikola Tesla after his experimentation with high frequency currents in an evacuated glass tube for the purpose of studying high voltage phenomena. The first practical plasma lamps were the sulfur lamps manufactured by Fusion Lighting. This lamp suffered a number of practical problems and did not prosper commercially. These problems have gradually been overcome by manufacturers such as Ceravision and Luxim, and high-efficiency plasma (HEP) lamps have been introduced to the general lighting market.