Plasma Science Saving Lives in the Home: Fact or Marketing Fiction

Can Plasmas Save Lives?

Plasmas can be very hostile environments so why would we want to create a plasma in our house, is this dangerous? In reality, plasmas are used for many useful things such as lighting. Fluorescent tubes contain plasma as well as the newer energy-saving lights. The plasma forms when an electrical current heats any free electrons; these hot electrons collide with the gas and knock off an extra electron from the gas forming a positive ion. A positive ion is a gas atom with an electron removed. Now we have two free electrons and a free ion. The free electrons are quickly heated in the electric field and cause more electrons and ions to appear. This is called an avalanche, and the effect is used in a Geiger counter to detect electrons from radioactive material. Detecting radioactivity can save lives, but a more important device is the smoke detector.

An Elephant on a Motorway

In a smoke detector a weak corona plasma is formed and current flows via electrons across the smoke detector. Normally, with no smoke the plasma current is undisturbed and a stable current is reached; but when the smoke enters the plasma region the electrons collide with the smoke particles. It is a little like elephants walking on a motorway, suddenly everything goes much slower. The plasma current drops and the smoke alarm sounds. So plasmas can save lives even in our house.

Plasma Cluster Based Ion Purifiers

A recent new technology uses the same idea of electrons colliding with dust particles. It is called an Ionic purifier. When the electrons collide with the dust they stick to the surface, this causes the dust clusters to become negatively charged. The ions also collide with the dust but the ions are much heavier and therefore much slower, so more electrons hit the dust than ions. In a purifier a weak plasma is formed and any dust particles present are charged up negatively. An electric field with a positive and negative side is set up and the dust is attracted to the positive side. The dust is then collected and removed from the air. This is very important as some people are allergic to dust and mites that float in the air.

Plasma Sterilization

The weak plasma also has some more useful effects. When the electrons are heated in the electric field they collide with gas atoms and molecules and knock off electrons, this is called ionization or ionization to our American cousins. But not all electron collisions successfully knock off the electron from the atom, some collisions just shake the atom or molecule and cause the electrons to enter an excited state. These atoms or molecules with excited electrons are called radicals. Radicals can collide with other gas atoms or molecules and form short-lived chemicals called metastable states. These metastable molecules or atoms are highly reactive because the electrons are excited and they will react with cells or other living organism, killing them. They do not travel far as they are short-lived so the effect is localized but careful design is required to prevent a build up of radicals that might be harmful. Normally, the metastable states quickly decay into harmless air molecules. The weak plasma can excite oxygen and turn it into a sterilizing agent which is short-lived. This cleans the air in the purifier of dangerous microbes that could harm your health.

I look forward to other new Plasma Technologies that can improve our lives and if you are interested to learn more about plasma science and technology then please visit my Blog.

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