Plasma is often stated as the fourth element and it consists of hot ionized gas or excited gas molecules created by electrical energy.

Just to note here that the other three elements of course being water, air and earth, whereas Plasma is neither gas or air but an element in its own right.

Plasma Balls, also called Plasma lamps and Plasma globes first widely appeared for retail in the 1980's and are more popular today than ever before.

The Plasma lamp was actually  invented in the late1800's by Nikola Tesla who was experimenting with high frequency currents of electricity in a vacuum  glass tube, scientifically called an "evacuated tube"  The Plasma Ball or lamp was actually first named by Tesla as "an inert gas discharge tube" for want of a better description.

Nikola Tesla 1856 -1943

Nikola Tesla was a Serbian-American electrical engineer and inventor, more notably he was the inventor of AC electrical power, generation and transmission, that is used world wide today.

Tesla's ingenuity led to the discovery of radio waves and their transmission, the  hypothesis of a practical television, the first practical working hydro-electric dams, remote and radio control, radar, X-rays and the ways and methods of utilizing electricity to the operators best and safest advantage.

It was in 1894 that Nikola Tesla had US Patent 514170 for the run up to the Plasma lamp, the Patent which is duplicated here...

...Patent for " Incandescent Electric Light  - Related to US454622; Incandescent electric lamps; Particular forms of the lamp in which a light giving small body or button of refractory material is supported by a conductor entering a very highly exhausted globe or receiver; Conducting screen surrounds the supporting conductor; Single node vacuum tube"

This Patent then was for the first high voltage discharge lamp similar to the Plasma Ball that we see today.

In fact Tesla had countless inventions and indeed many Patents on them as well, these included work on the carbon button lamp and electrical resonance in various types of lighting, also Patents were applied for his construction of generators and transformers.

After Tesla's death in 1943 many of his research papers and other important documents mysteriously disappeared and have not been seen again.

It would have been too corny for me to have said "...and these documents have not seen the light of day since "

Plasma Balls then are closed spheres that are filled with a mixture of different inert  non reactive gases that emit bright streams of plasma when exited with an electrical current.  The gas has to be at low pressure  so that it can be broken down by the current in order to produce the plasma streams.

A voltage of alternating current is passed through the gas, this voltage is usually in the 35Khz range and is generated by a transformer that plugs into an AC socket.

If the gas mixture and the pressure of the gas in the sphere is not correct, then the display of plasma streams can be very weak, very dim or both or the streams will have no color in them.

The inert gas elements that are generally used in Plasma Balls are Xenon, Neon and Krypton or a mixture of these, but generally all the mixtures contain neon so that a vivid stream of colored plasma is created.

Below is a list of the most widely used gases and the colors that they can produce in a Plasma ball, it must be stressed again though that a single gas is not really used as such but moreover a delicately balanced mixture of two or more gases together.

Helium (He) Produces a very bright blue-purple Plasma stream.

Neon (Ne) Produces a really bright red & orange although blurred effect plasma stream with bright pink & orange color at the ends.

Xenon (Xe) On its own produces quite a dim and unexciting bluish white or bluish grey color.

Krypton (Kr) On its own produces quite a dim and thin white with pale blue hue plasma stream.

Carbon Dioxide (Co2) Produces quite a bright glow a whitish or blue-white color.

Nitrogen (N2) Produces quite a bright whitish pink with a blue-purple tinge.

Argon (Ar) The plasma stream produced from Argon is a nice violet-lavender mixed with blue tinges at the ends.

Below is a 41 second "YouTube" video of an eight inch diameter plasma ball in action with a close up shot of the spherical electrode in the center that emits the plasma streams...weird isn't it !

In the center of the ball this small electrode also spherical in shape is what emits the current flows  into the gas.  This creates the hundreds of constantly moving colorful plasma streams that extend outwards to the inner surface of the ball, the ball itself acts as an insulator.

The beams of plasma emit from the electrode at 360 degrees with a bright blue-lavender color that changes to pink as it earths out on the inside edge of the ball.

When a good earthed object such as a person touches the ball, the frequency of the discharged plasma changes and a percentage of it collates into a single beam of bright plasma and concentrates on the point of contact ie: the persons hand or finger that's touching the ball.

There is no discharge of electrical current through the glass, when it is touched, so the person does not in effect get an electric shock when they do touch the ball.

The Ball does not block the electromagnetic field that is created by the plasma as it flows through the gas although the gas itself acting as an insulator does block the actual power of the current.

As with most electrical appliances there is always a potential hazard if not handled with some care.  The Plasma ball although quite safe can still present a few issues with other electrical devices if they are too close to its vicinity.

The electromagnetic field that the plasma ball emits is quite slight but may still be enough to effect computers, mobile phone signals, MP3 players and other electrical equipment if they are too close to the ball when in operation.

People with a pacemaker should not touch a plasma ball due to the possibility that the electromagnetic field could cause fluctuations in the pacemakers circuitry.

If a coin or other metal object is placed on the ball there is a chance of electrical shock discharge through the ball via the coin even though the ball itself is not a conductor. Care and responsibility with a little common sense should be used though as with all electrical devices.

Plasma Balls are sold as novelties and hold fantastic curiosity value for all that see one in operation.  They do not serve any purpose other than a visual display of light and color.

On the scientific level these Plasma Balls of course offer a brilliant method of showing how electricity discharges though gas and hence can be very educational.

The Plasma Ball does not emit enough light to illuminate a dark room or even its surrounding area but recently manufacturers have made a Plasma 'lamp' that does emit enough light for the purpose of acting like a dim night light.

The novelty Plasma Ball as we know today was devised by Bill Parker in 1970 and it wasn't until 1980 that the glass orbs and complex integrated circuits along with the exacting mixtures of gases were perfected to create the dazzling array of color and effects that we see in today's Plasma Balls.

The technology utilized to create the various mixtures of high purity gases that are used in today's Plasma Balls were not around in Tesla's era which is why Tesla himself didn't invent the Plasma Ball as we know it, he was just the 'Father' of the idea.

Plasma Balls are widely available from such places as gadget shops and online off the internet.  The image below shows a Plasma Ball that works of a USB cable that plugs into a PC, the electromagnetic field is shielded so it wont interfere with the Computers electronics.

Available online from these internet stores. Just click the plasma balls below

     Iwantoneofthose.com        ThinkGeek.com

      Walmart.com          Scientificsonline.com          Ebay.com

I am in no way affiliated with these stores, Nor do I  have any business transactions with them and therefore I cannot order a plasma ball for you, so please don't ask Thank You !