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Kristian Olaf Birkeland (13 December 1867 – 15 June 1917) was a Norwegian scientist. He is best remembered as the person who first elucidated the nature of the Aurora borealis. In order to fund his research on the aurorae, he invented the electromagnetic cannon and the Birkeland-Eyde process of fixing nitrogen from the air. Birkeland was nominated for the Nobel Prize seven times. Birkeland was born in Christiania (Oslo today) and wrote his first scientific paper at the age of 18. Birkeland
married Ida Charlotte Hammer in May 1905, they had no children and due
to Birkeland's work, they finally divorced in 1911. Suffering from severe paranoia due to his use of Veronal as a sleeping aid, he died under mysterious circumstances in his room in the Hotel Seiyoken in Tokyo while visiting colleagues at the University of Tokyo.
A post-mortem revealed that Birkeland had taken 10g of veronal the
night he died, instead of the 0.5g recommended. The time of death was
estimated at 7am on 15 June, 1917. Some authors have claimed that he committed suicide. He
organized several expeditions to Norway's high-latitude regions where
he established a network of observatories under the auroral regions to
collect magnetic field data.
The results of the Norwegian Polar Expedition conducted from 1899 to
1900 contained the first determination of the global pattern of
electric currents in the polar region from ground magnetic field
measurements. The discovery of X-rays inspired
Birkeland to develop vacuum chambers to study the influence of magnets
on cathode rays. Birkeland noticed that an electron beam directed
toward a magnetised terrella was
guided toward the magnetic poles and produced rings of light around the
poles and concluded that the aurora could be produced in a similar way.
He developed a theory in which energetic electrons were ejected from
sunspots on the solar surface, directed to the Earth, and guided to the Earth's polar regions by the geomagnetic field where they produced the visible aurora. The
scale of Birkeland's research enterprises was such that funding became
an overwhelming obstacle. Recognizing that technological invention
could bring wealth, he developed an electromagnetic cannon and,
with some investors, formed a firearms company. The coil-gun worked,
except the high muzzle velocities he predicted (600 m/s) were not
produced. The most he could get from his largest machine was 100 m/s,
corresponding to a disappointing projectile range of only 1 km. So he
renamed the device an aerial torpedo and
arranged a demonstration with the express aim of selling the company.
At the demonstration, one of the coils shorted and produced a
sensational inductive arc complete with noise, flame, and smoke. This
was the first failure of any of the launchers that Birkeland had built.
It could easily have been repaired and another demonstration organized. However, fate intervened in the form of an engineer named Sam Eyde.
At a dinner party only one week later, Eyde told Birkeland that there
was an industrial need for the biggest flash of lightning that can be
brought down to Earth in order to make artificial fertilizer.
Birkeland's reply was, "I have it!" There were no more attempts to sell
the firearms company, and he worked with Eyde only long enough to build
a plasma arc device for the nitrogen fixation process.
The pair worked to develop the prototype furnace into a design that was
economically viable for large-scale manufacture. The resulting company, Norsk Hydro, hugely enriched Norway, and Birkeland then enjoyed adequate funding for research, his only real interest. The
fact that Birkeland joined with Eyde as a business partner appears to
have been one of the reasons why Birkeland was unsuccessful in being
awarded the Nobel Prize for his idea. Eyde wanted to be nominated along
with Birkeland; however, the Nobel Prize is designed to recognise the
original idea, not any commercial applications. This resulted in a
possibly contentious nomination, and this combined with the fact that
at that time relations between Sweden and Norway were delicate, meant
that he wasn't nominated by the committee. In
1913, Birkeland may have been the first to predict that plasma was
ubiquitous in space. He wrote: "It seems to be a natural consequence of
our points of view to assume that the whole of space is filled with
electrons and flying electric ions of all kinds. We have assumed that
each stellar system in evolutions throws off electric corpuscles into
space. It does not seem unreasonable therefore to think that the
greater part of the material masses in the universe is found, not in
the solar systems or nebulae, but in 'empty' space." In 1916, Birkeland was probably the first person to successfully predict that the solar wind behaves
as do all charged particles in an electric field: "From a physical
point of view it is most probable that solar rays are neither
exclusively negative nor positive rays, but of both kinds" In other words, the Solar Wind consists of both negative electrons and positive ions. Birkeland suggested that polar electric currents --
today referred to as auroral electrojets -- were connected to a system
of currents that flowed along geomagnetic field lines into and away
from the polar region. He provided a diagram of field-aligned currents
in his book, The Norwegian Aurora Polaris Expedition 1902-1903.
This book contains chapters on magnetic storms on the Earth and their relationship to the Sun, the origin of the Sun itself, Halley's comet, and the rings of Saturn.
Birkeland's vision of field-aligned currents became the source of a
controversy that continued for a quarter of a century, because their
existence could not be confirmed from ground-based measurements alone.
The proof of Birkeland's field-aligned currents could come only from
observations made above the ionosphere with satellites. A magnetometer on board
a U.S. Navy navigation satellite launched in 1963 observed magnetic
disturbances on nearly every pass over the high-latitude regions of the
Earth. The magnetic disturbances were originally interpreted as
hydromagnetic waves, but it was soon realized that they were due to
field-aligned or Birkeland currents. The first complete map of the statistical location of Birkeland currents in the Earth's polar region was developed in 1974 by A.J. Zmuda and J.C. Armstrong and refined in 1976 by T. Iijima and T.A. Potemra. |