In a world of evergrowing tension, international trust is at an all time low. With the recent Russian diplomat expulsions and resulting retaliatory expulsion of mostly US diplomats from Russia, there is a considerable political conflict brewing. This is particularity worrying as currently over 93% of the world’s military nuclear capacity is held between Russia and the United States. Russia currently has about 7000 nuclear missiles and the US has approximately 6800. The rest of the world’s cumulative might barely breaches 1000.
Thorium dioxide (ThO2), also known as thoria, is a very important nuclear material. It itself is not actually fissile (able to sustain a nuclear fission reaction) but anyone who knows their isotopes will notice something about thorium-232. If it absorbs a neutron it will become thorium-233 and then, in this unstable state, it’s just a β– decay away from becoming uranium-233 which is a fissile material. As a result uranium dioxide (UO2) fuel rods can be blended with thorium dioxide in order to reduce the pure fuel needed in the reactor. Considering that thorium is about three times as common as uranium it certainly helps reduce some of the mining and refining costs associated with nuclear activity.
When plasmas are compressed into multi-kilojoule lasers, some of the largest in the world, it is normally possible to get some nuclear fusion occurring. The neutrons produced in this fusion are normally produced in yields of about 105 neutrons per joule. When fusion is specifically sought for, some incredible events have been produced. By blasting lasers into a compressible fuel pellet of deuterium and tritium an implosion was produced at a the National Ignition Facility (NIF) in California which produced 7.6 × 1015 neutrons while only using 1.9 × 106 joule laser pulses. This is about 109 neutrons per joule. This event actually holds the record for the highest neutron number to joule ratio of any system in the world.
Laser pulses on the femtosecond timescale and with many terawatts of power have allowed the scientific community to examine all manner of extreme physical effects. It is the production of these lasers which has brought about the very recent field of experimental astrophysics, something that would have been scoffed at fifty years ago. Many of the different laser applications from medical physics to nuclear physics can be summed up as transferring a large amount of energy from electromagnetic waves to particles. These laser matter interactions are by no means simple, but are certainly a fundamental part of physics especially if we want to properly apply the technology these lasers are providing.
It is the traditional super villain plan to try to blow something up with a laser, whether that be the moon, the hero or a bank wall, lasers as tools of destruction are often seen in our media. The fact is, scientists are people too. Ever since lasers were first invented experiments have been performed to see if lasers can be used to effectively destroy things. Perhaps I’m not giving enough credit, understanding the laser breakdown threshold really creating and using lasers must safer. Also techniques such as laser induced breakdown spectroscopy involve the laser to atomise a sample for the spectrographic technique and laser machining can use the controlled ablation of a material to shape it.
Satellites certainty live an interesting life whizzing around the Earth; getting half frozen and half baked every orbit; trying to dodge all the other useless junk flying around as well; occasionally getting an order to rotate an arcsecond clockwise or something like that. They also get to be our first level of sensing when it comes to intense radio waves heading for Earth. Continue reading Studying Solar Radio Burst By Magnetic Reconnection
I consider it a slight shame that the layers of the Sun are not as widely known as the layers of the Earth. Most people could list the inner core, outer core, mantle and crust; but very few know that the layers of the Sun go: core, radiative zone, convection zone, photosphere, chromosphere and corona. The solar surface is defined as the boundary between the convection zone and photosphere so perhaps it is best to imagine the layers above his as the thin “atmosphere” of the Sun being only a few thousand miles thick (as opposed to radius to the solar surface which is about 400,000 miles).