Derek Robinson (physicist)
Encyclopedia
Derek Charles Robinson FRS (27 May 1941 – 2 December 2002) was a physicist
who worked in the UK fusion power
program for most of his professional career. Studying turbulence in the UK's ZETA
reactor, he helped develop the reversed field pinch
concept, an area of study to this day. He is best known for his role in taking a critical measurement on the T-3 device in the USSR in 1969 that established the tokamak
as the primary magnetic fusion energy device to this day. He was also instrumental in the development of the spherical tokamak
design though the construction of the START
device, and its follow-on, MAST
. Robinson was in charge of portions of the UK Atomic Energy Authority's fusion program from 1979 until he took over the entire program in 1996 before his death in 2002.
. As his father was in the Royal Air Force
, Robinson often moved and spent an average of eighteen months at any one primary school. At secondary school he shone at science and mathematics and decided to follow a career in physics
. His love of church and particularly organ music also stemmed from this period, when he sang in his local church choir.
He entered the Victoria University of Manchester
and graduated as the top-of-the-year student in physics. Robinson's professor Brian Flowers
introduced him to the researchers at the Atomic Energy Research Establishment
, better known simply as "Harwell". He was taken on to complete his PhD in Physics under the direction of Sam Edwards
.
machine. When ZETA first started operation in the summer of 1957, it gave off large bursts of neutron
s, the most obvious sign of nuclear fusion
reactions. Measurements of the plasma
temperature supported this result; the machine appeared to reach 5 million degrees, hot enough to be generating fusion at a low rate, within an order of two of the number of neutrons one would expect to generate at that temperature.
When the first results from ZETA were being publicly released at a press event in January 1958, John Cockcroft
was first evasive on the issue, but eventually stated he was 90% sure they came from fusion events. This turned out to be incorrect. The actual temperature of the reactor was much lower than the measurements suggested, far too low for fusion to be taking place. The claims of fusion had to be retracted in May, a major humiliation.
Over time the nature of the neutrons was explored and came to be understood as isolated events caused by instabilities inside the plasma. Earlier "gross" instabilities had been successfully dealt with in ZETA, but correcting these had simply turned up another set to be fixed. The new ones were being caused by turbulence
within the plasma. Some progress on suppressing these had been made by E. P. Butt and others, but they were not well understood.
Robinson was put on the task of better understanding the nature of the turbulence, running a series of experiments to characterize it. These experiments led to a better understanding of the theoretical nature of the problem, which in turn led to major work by John Bryan Taylor
on a general theory of high-current electric discharges in magnetic fields. This work was a major advance in plasma physics, and through it introduced the concept of reversed field pinch
, a field of study to this day.
As the nature of these problems became clear, the ZETA team turned from attempting fusion to developing dramatically improved diagnostic tools for characterizing the plasma. Instead of measuring the spectroscopy of the ions, it is possible to directly measure the velocity of electrons through Thomson scattering
. However, this requires a bright and highly monochromatic light source to be effective. The introduction of the laser
in the 1960s provided just such a source, and beginning in 1964 the Harwell team became experts in this system.
device. In configuration, the tokamak is largely identical to the z-pinch
devices like ZETA, consisting of a ring of magnets surrounding a toroidal vacuum tube, with a large transformer used to induce current into the plasma. The magnetic field of the two sources mixed to produce a single helical field that winds around the plasma. Where the two systems differed was primarily in the ratio of the power of the fields; ZETA's field was generated almost entirely by the transformer current, while the tokamak used more powerful ring magnets to balance the two more closely. This seemingly minor change has enormous effects on the dynamics of the plasma; ZETA's helix wound slowly around the plasma, the tokamak's was fairly "twisty". This is measured by the "safety factor
".
By the mid-1960s, experimental machines demonstrated that the tokamak concept was a dramatic improvement over older designs. However, the Soviets waited, perhaps wanting to avoid another ZETA debacle, until they were absolutely sure their machines were producing the numbers the measurements suggested they were. This work carried on into 1967 and 68, which happened to correspond with the 3rd International Conference on Plasma Physics and Controlled Fusion Research, being held in Novosibirsk in August 1968.
When the numbers from the latest T-3 reactor were announced at the meeting - plasma temperatures of 10 million degrees, confinement times over 10 milliseconds and clear signs of fusion - the fusion community was stunned. The machines were at least an order of magnitude better than anyone else's device, including ones of much greater size and theoretical performance. The question then became whether or not the results were real, and scepticism abounded.
Lev Artsimovitch addressed this concern, inviting "Bas" Pease
to bring the ZETA team to the T-3 at the Kurchatov Institute
in Moscow
. Coming at the height of the Cold War
, this was a unique opportunity. But British concerns about possible defection meant that UK subjects with valuable knowledge could only travel to the USSR if "properly accompanied by a reliable person". Robinson solved this problem by marrying Marion Quarmby in 1968, while taking a crash course in Russian.
The "Culham Five" team, led by Nicol Peacock, arrived in 1969. Their experiments did not go well, initially being unable to see the light over the background. Robinson led the effort to improve the power of the ruby laser
, eventually increasing it by 100 times. Now the signal was clear, validating the Soviet results with measurements on the order of 20 million degrees. Their paper, published in Nature in November 1969, led to a revolution in fusion research, as practically every other design concept was dumped in favour of tokamaks.
His search for alternate solutions meant he was particularly receptive to Martin Peng of the Oak Ridge National Laboratory
(ORNL) in the US, who was trying to drum up interest in the spherical tokamak
(STs) concept. ST's were essentially small tokamaks, but a combination of features suggested they would offer greatly improved performance over conventional designs. ORNL had designed a machine to test the concept, the "STX", but were unable to secure funding to build the machine.
Robinson was able to secure £10 million, enough to build the vacuum chamber and most of the support equipment. Other equipment, including a neutral beam injector, were "loaned" from ORLN to keep to the budget. The machine, START
, went into operation in 1991 and immediately turned in results that met or beat practically every other machine in the world, including ones that cost many times more. START's success led to similar machines around the world, including Culham's own MAST
.
(JET) project, after Culham was selected as the site for its construction. Six years later he was appointed a member of its board. He was elected fellow of the Royal Society
in 1994, and became fusion director at UKAEA in 1996. Robinson, who was a fellow of the Institute of Physics, was also actively involved in the design of the International Thermonuclear Experimental Reactor (ITER).
Robinson died of cancer
at the Sobell House Hospice
in Oxford. He was survived by his wife Marion and daughter Nicola.
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
who worked in the UK fusion power
Fusion power
Fusion power is the power generated by nuclear fusion processes. In fusion reactions two light atomic nuclei fuse together to form a heavier nucleus . In doing so they release a comparatively large amount of energy arising from the binding energy due to the strong nuclear force which is manifested...
program for most of his professional career. Studying turbulence in the UK's ZETA
ZETA
ZETA, short for "Zero-Energy Toroidal Assembly", was a major experiment in the early history of fusion power research. It was the ultimate device in a series of UK designs using the Z-pinch confinement technique, and the first large-scale fusion machine to be built...
reactor, he helped develop the reversed field pinch
Reversed field pinch
A reversed-field pinch is a device used to produce and contain near-thermonuclear plasmas. It is a toroidal pinch which uses a unique magnetic field configuration as a scheme to magnetically confine a plasma, primarily to study magnetic fusion energy. Its magnetic geometry is somewhat different...
concept, an area of study to this day. He is best known for his role in taking a critical measurement on the T-3 device in the USSR in 1969 that established the tokamak
Tokamak
A tokamak is a device using a magnetic field to confine a plasma in the shape of a torus . Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape...
as the primary magnetic fusion energy device to this day. He was also instrumental in the development of the spherical tokamak
Spherical tokamak
A spherical tokamak is a type of fusion power device based on the tokamak principle. It is notable for its very narrow profile, or "aspect ratio". A traditional tokamak has a toroidal confinement area that gives it an overall shape similar to a donut, complete with a large hole in the middle...
design though the construction of the START
Small Tight Aspect Ratio Tokamak
The Small Tight Aspect Ratio Tokamak, or START was a nuclear fusion experiment that used magnetic confinement to hold plasma. The experiment began at the Culham Science Centre in the United Kingdom in 1991 and was retired in 1998. It was built as a low cost design, largely using parts already...
device, and its follow-on, MAST
Mega Ampere Spherical Tokamak
The Mega Ampere Spherical Tokamak, or MAST experiment is a nuclear fusion experiment in operation at Culham, Oxfordshire, England since December 1999. It follows the highly successful START experiment...
. Robinson was in charge of portions of the UK Atomic Energy Authority's fusion program from 1979 until he took over the entire program in 1996 before his death in 2002.
Early years
Robinson was born in Douglas on the Isle of ManIsle of Man
The Isle of Man , otherwise known simply as Mann , is a self-governing British Crown Dependency, located in the Irish Sea between the islands of Great Britain and Ireland, within the British Isles. The head of state is Queen Elizabeth II, who holds the title of Lord of Mann. The Lord of Mann is...
. As his father was in the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
, Robinson often moved and spent an average of eighteen months at any one primary school. At secondary school he shone at science and mathematics and decided to follow a career in physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
. His love of church and particularly organ music also stemmed from this period, when he sang in his local church choir.
He entered the Victoria University of Manchester
Victoria University of Manchester
The Victoria University of Manchester was a university in Manchester, England. On 1 October 2004 it merged with the University of Manchester Institute of Science and Technology to form a new entity, "The University of Manchester".-1851 - 1951:The University was founded in 1851 as Owens College,...
and graduated as the top-of-the-year student in physics. Robinson's professor Brian Flowers
Brian Flowers, Baron Flowers
Brian Hilton Flowers, Baron Flowers FRS was a British physicist and academican.-Early life and studies:The son of Reverend Harold Joseph Flowers, he was educated at the Bishop Gore School in Swansea and at Gonville and Caius College, Cambridge, where he graduated with a Master of Arts...
introduced him to the researchers at the Atomic Energy Research Establishment
Atomic Energy Research Establishment
The Atomic Energy Research Establishment near Harwell, Oxfordshire, was the main centre for atomic energy research and development in the United Kingdom from the 1940s to the 1990s.-Founding:...
, better known simply as "Harwell". He was taken on to complete his PhD in Physics under the direction of Sam Edwards
Sam Edwards (physicist)
Sir Samuel Frederick Edwards FLSW FRS is a British physicist.-Early life and studies:Sir Samuel was born on 1 February 1928 in Swansea, the son of Richard and Mary Jane Edwards....
.
ZETA's neutrons
Harwell operated the largest, most powerful and most sophisticated fusion device, the ZETAZETA
ZETA, short for "Zero-Energy Toroidal Assembly", was a major experiment in the early history of fusion power research. It was the ultimate device in a series of UK designs using the Z-pinch confinement technique, and the first large-scale fusion machine to be built...
machine. When ZETA first started operation in the summer of 1957, it gave off large bursts of neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
s, the most obvious sign of nuclear fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
reactions. Measurements of the plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
temperature supported this result; the machine appeared to reach 5 million degrees, hot enough to be generating fusion at a low rate, within an order of two of the number of neutrons one would expect to generate at that temperature.
When the first results from ZETA were being publicly released at a press event in January 1958, John Cockcroft
John Cockcroft
Sir John Douglas Cockcroft OM KCB CBE FRS was a British physicist. He shared the Nobel Prize in Physics for splitting the atomic nucleus with Ernest Walton, and was instrumental in the development of nuclear power....
was first evasive on the issue, but eventually stated he was 90% sure they came from fusion events. This turned out to be incorrect. The actual temperature of the reactor was much lower than the measurements suggested, far too low for fusion to be taking place. The claims of fusion had to be retracted in May, a major humiliation.
Over time the nature of the neutrons was explored and came to be understood as isolated events caused by instabilities inside the plasma. Earlier "gross" instabilities had been successfully dealt with in ZETA, but correcting these had simply turned up another set to be fixed. The new ones were being caused by turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
within the plasma. Some progress on suppressing these had been made by E. P. Butt and others, but they were not well understood.
Robinson was put on the task of better understanding the nature of the turbulence, running a series of experiments to characterize it. These experiments led to a better understanding of the theoretical nature of the problem, which in turn led to major work by John Bryan Taylor
John Bryan Taylor
John Bryan Taylor is a British physicist known for his important contributions to plasma physics and their application in the field of fusion energy. Notable among these is the development of the "Taylor state", describing a minimum-energy configuration that conserves magnetic helicity...
on a general theory of high-current electric discharges in magnetic fields. This work was a major advance in plasma physics, and through it introduced the concept of reversed field pinch
Reversed field pinch
A reversed-field pinch is a device used to produce and contain near-thermonuclear plasmas. It is a toroidal pinch which uses a unique magnetic field configuration as a scheme to magnetically confine a plasma, primarily to study magnetic fusion energy. Its magnetic geometry is somewhat different...
, a field of study to this day.
As the nature of these problems became clear, the ZETA team turned from attempting fusion to developing dramatically improved diagnostic tools for characterizing the plasma. Instead of measuring the spectroscopy of the ions, it is possible to directly measure the velocity of electrons through Thomson scattering
Thomson scattering
Thomson scattering is the elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism. It is just the low-energy limit of Compton scattering: the particle kinetic energy and photon frequency are the same before and after the scattering...
. However, this requires a bright and highly monochromatic light source to be effective. The introduction of the laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
in the 1960s provided just such a source, and beginning in 1964 the Harwell team became experts in this system.
Novosibirsk and T-3
From the mid-1950s the Soviets had been quietly developing the tokamakTokamak
A tokamak is a device using a magnetic field to confine a plasma in the shape of a torus . Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape...
device. In configuration, the tokamak is largely identical to the z-pinch
Z-pinch
In fusion power research, the Z-pinch, also known as zeta pinch or Bennett pinch , is a type of plasma confinement system that uses an electrical current in the plasma to generate a magnetic field that compresses it...
devices like ZETA, consisting of a ring of magnets surrounding a toroidal vacuum tube, with a large transformer used to induce current into the plasma. The magnetic field of the two sources mixed to produce a single helical field that winds around the plasma. Where the two systems differed was primarily in the ratio of the power of the fields; ZETA's field was generated almost entirely by the transformer current, while the tokamak used more powerful ring magnets to balance the two more closely. This seemingly minor change has enormous effects on the dynamics of the plasma; ZETA's helix wound slowly around the plasma, the tokamak's was fairly "twisty". This is measured by the "safety factor
Safety factor (plasma physics)
In a toroidal fusion power reactor, the magnetic fields confining the plasma are formed in a helical shape, winding around the interior of the reactor...
".
By the mid-1960s, experimental machines demonstrated that the tokamak concept was a dramatic improvement over older designs. However, the Soviets waited, perhaps wanting to avoid another ZETA debacle, until they were absolutely sure their machines were producing the numbers the measurements suggested they were. This work carried on into 1967 and 68, which happened to correspond with the 3rd International Conference on Plasma Physics and Controlled Fusion Research, being held in Novosibirsk in August 1968.
When the numbers from the latest T-3 reactor were announced at the meeting - plasma temperatures of 10 million degrees, confinement times over 10 milliseconds and clear signs of fusion - the fusion community was stunned. The machines were at least an order of magnitude better than anyone else's device, including ones of much greater size and theoretical performance. The question then became whether or not the results were real, and scepticism abounded.
Lev Artsimovitch addressed this concern, inviting "Bas" Pease
Bas Pease
Rendel Sebastian "Bas" Pease FRS was a British physicist.Pease's father was the geneticist Michael Pease, son of Edward Reynolds Pease. His mother was Helen Bowen Wedgwood, daughter of Josiah Wedgwood IV...
to bring the ZETA team to the T-3 at the Kurchatov Institute
Kurchatov Institute
The Kurchatov Institute is Russia's leading research and development institution in the field of nuclear energy. In the Soviet Union it was known as I. V. Kurchatov Institute of Atomic Energy , abbreviated KIAE . It is named after Igor Kurchatov....
in Moscow
Moscow
Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...
. Coming at the height of the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
, this was a unique opportunity. But British concerns about possible defection meant that UK subjects with valuable knowledge could only travel to the USSR if "properly accompanied by a reliable person". Robinson solved this problem by marrying Marion Quarmby in 1968, while taking a crash course in Russian.
The "Culham Five" team, led by Nicol Peacock, arrived in 1969. Their experiments did not go well, initially being unable to see the light over the background. Robinson led the effort to improve the power of the ruby laser
Ruby laser
A ruby laser is a solid-state laser that uses a synthetic ruby crystal as its gain medium. The first working laser was a ruby laser made by Theodore H. "Ted" Maiman at Hughes Research Laboratories on May 16, 1960....
, eventually increasing it by 100 times. Now the signal was clear, validating the Soviet results with measurements on the order of 20 million degrees. Their paper, published in Nature in November 1969, led to a revolution in fusion research, as practically every other design concept was dumped in favour of tokamaks.
- "Derek Robinson was highly respected in Russia ever since his visit in 1968, his measurements of the electron temperature profiles in the T-3 plasma led to the beginning of active research on tokamaks all over the world. Derek was known for his brilliant scientific research and bright personality. He was an extremely friendly, charming, clever and intelligent person, who will be remembered by all who met him." - Evgeny Velikhov, president of the Kurchatov Institute
COMPASS and STs
On his return to the UK in 1970, Robinson moved to the UKAEA laboratory in Culham, which was gathering together the previously spread-out fusion efforts. He led the effort to build the UK's own tokamak, COMPASS. When experiments suggested that non-circular confinement areas would have better performance, Robinson led the effort to convert COMPASS to COMPASS-D, which featured a tear-drop shaped confinement area. COMPASS-D validated the concept. The D-shaped plasma area is a feature of all modern tokamak designs.His search for alternate solutions meant he was particularly receptive to Martin Peng of the Oak Ridge National Laboratory
Oak Ridge National Laboratory
Oak Ridge National Laboratory is a multiprogram science and technology national laboratory managed for the United States Department of Energy by UT-Battelle. ORNL is the DOE's largest science and energy laboratory. ORNL is located in Oak Ridge, Tennessee, near Knoxville...
(ORNL) in the US, who was trying to drum up interest in the spherical tokamak
Spherical tokamak
A spherical tokamak is a type of fusion power device based on the tokamak principle. It is notable for its very narrow profile, or "aspect ratio". A traditional tokamak has a toroidal confinement area that gives it an overall shape similar to a donut, complete with a large hole in the middle...
(STs) concept. ST's were essentially small tokamaks, but a combination of features suggested they would offer greatly improved performance over conventional designs. ORNL had designed a machine to test the concept, the "STX", but were unable to secure funding to build the machine.
Robinson was able to secure £10 million, enough to build the vacuum chamber and most of the support equipment. Other equipment, including a neutral beam injector, were "loaned" from ORLN to keep to the budget. The machine, START
Small Tight Aspect Ratio Tokamak
The Small Tight Aspect Ratio Tokamak, or START was a nuclear fusion experiment that used magnetic confinement to hold plasma. The experiment began at the Culham Science Centre in the United Kingdom in 1991 and was retired in 1998. It was built as a low cost design, largely using parts already...
, went into operation in 1991 and immediately turned in results that met or beat practically every other machine in the world, including ones that cost many times more. START's success led to similar machines around the world, including Culham's own MAST
Mega Ampere Spherical Tokamak
The Mega Ampere Spherical Tokamak, or MAST experiment is a nuclear fusion experiment in operation at Culham, Oxfordshire, England since December 1999. It follows the highly successful START experiment...
.
JET and UKAEA directorship
In 1990 Robinson was appointed UK member to the Joint European TorusJoint European Torus
JET, the Joint European Torus, is the largest magnetic confinement plasma physics experiment worldwide currently in operation. Its main purpose is to open the way to future nuclear fusion experimental tokamak reactors such as ITER and :DEMO....
(JET) project, after Culham was selected as the site for its construction. Six years later he was appointed a member of its board. He was elected fellow of the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
in 1994, and became fusion director at UKAEA in 1996. Robinson, who was a fellow of the Institute of Physics, was also actively involved in the design of the International Thermonuclear Experimental Reactor (ITER).
Robinson died of cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
at the Sobell House Hospice
Sobell House Hospice
The Sir Michael Sobell House Hospice is an Oxford based Hospice serving the residents of Oxfordshire affected by life-limiting illness.In 1976, Sir Michael Sobell and the friends of Sobell House donated the funds to help build the original hospice...
in Oxford. He was survived by his wife Marion and daughter Nicola.