Laser
Question:
Solar-pumped laser medium contains various rare metals such as
Chromium, Neodymium, Yttrium.
Struggles for these rare metals become fierce wordwide. Are there sufficient resources for laser medium?
Answer:
Question:
Is running cost of a solar-pumped-laser device free?
Don’t you need energy for sun-autoguider or cleaning cost of a Fresnel lens (especially in a desert) ?
Answer:
An article “An economical “Solar-pumped laser” produces ultra high temperature” shows that solar-pumped-laser realized ultrahigh-temperature which is impossible with simple concentration of sunlight.
The following movie is an experiment of solar-pumped-laser at Tokyo
Institute of Technology in January 2009. Output of laser was 50W. It can drill a hole on a 0.1mm-thick stainless plate easily.
The next movie shows deoxidation of magnesium oxide with
solar-pumped-laser. You will see the smoke from MgO at the instance
when the laser is correctly focused. The output is not enough for commercial smelting, but deoxidation itself is possible.
An article “Can a laser smelt magnesium?” explains that laser can evaporate the surface layer of the powder of magnesium oxide, and extract metal magnesium.
The following movie shows the moment that magnesium oxide vaporizes with laser for 0.5sec (1/60 high-speed videography). When magnesium oxide vaporizes in an instant, evaporated materials rise vertically. Therefore we can extract specified elements easily.
30% of collected materials are magnesium oxide, and 70% are metal magnesium. It means we can get 70% pure magnesium with laser smelting. 70% is enough for fuel. By comparison, purity of magnesium with Pidgeon method is 80% at the first stage, and then refinement process makes it purer.
Question:
How much is conversion efficiency of magnesium with solar-pumped-laser smelting?
Answer:
Carbon dioxide gas laser smelts magnesium
We have verified that we could obtain 400W-1kW level of power from a solar-energy-pumped laser. Following this result, we went on to conduct another experiment, using a different type of commercial laser, in order to see if we could in fact obtain magnesium. We illuminated magnesium oxide powder with a 1kW carbon dioxide gas laser for 0.2 seconds. This evaporated the surface layer of the powder to produce gas, and we verified that 30% of the gas was magnesium atoms. What is important here is how efficiently we can obtain pure magnesium. The energy reduction efficiency is defined as the ratio of the amount of energy produced by burning magnesium to the amount of laser energy required to produce the magnesium. The larger this efficiency, the better. The efficiency we obtained from the experiment was 45%, which is very close to our target of 50%.
If magnesium oxide is given an energy corresponding to 20,000 °C, the bond between its oxygen and magnesium would be broken naturally. It means we can smelt magnesium with no catalyst. Is it possible to inject an energy which is equivalent to 20,000 °C?
You must have played with a magnifying lens to collect the sun light to burn a sheet of paper when you were a child. There is a theoretical upper limit in the temperature obtained by focusing the sun light, which is 6,000 °C. What this means is that no matter how much of the sun light is focused, it is not possible to surpass the temperature of its source, the sun. However, the human wisdom makes it possible to exceed this limit. It is “solar-pumped laser”.
Recent Comments