On your wavelength

Interactions: Juan Knaster

Post by Giulia Pacchioni

Juan Knaster, project leader of IFMIF/EVEDA, answers our questions.
Knaster3What made you want to be a physicist?

Since childhood I have been obsessed with nature around me. Watching insect life, flowers, clouds moving, stars, moon, sunsets… Certainly Sagan’s television documentaries ‘Cosmos’ in the early 80s made a breakthrough in my spirit, but possibly the reading a few years later of the Spanish translation of Gamow’s Biography of Physics led me to be interested in nuclear fusion.

Gamow is the γ of the revolutionary αβγ-paper that unravelled nucleosynthesis in stars; possibly this led me unconsciously to my professional drive towards nuclear fusion from my teenage years, concurrently with the 80s Reagan–Gorbachov political move towards the research world’s adventure of ITER. I dreamt since I was a teenager to work for ITER. As soon as I finished my studies, I joined nuclear fusion research in CIEMAT in the last phases of design and start of construction of the TJ-II, the successful Spanish stellarator which remains in operation. After few years in CERN, where I matured professionally in the best possible environment I could have dreamt of, I re-joined the world’s fusion program through ITER.

I studied physics wishing to work for this beautiful dream of human kind, as old as humanity, of harnessing the fire of stars, and we are now very close! ITER will make a breakthrough in human history, since we will harness fire for the 2nd time in our history on Earth: this time the real one. Coming back to the question, before I keep on digressing… Fusion energy development led me to become a physicist.

Which historical figure would you most like to have dinner with — and why?

That’s a tricky question. I don’t think there is only one historical figure I wish to have dinner with.

I am fascinated with Neoplatonism, which was the philosophical consolidation of Gnosticism, which we could understand as the esoteric branch of a new religion, Christianity, that they attempted to eradicate following Council of Nicaea in 325 a.d. The line of thought of ‘oneness’ in the Universe, with humans  being not only observers, but very special actors in this united perception, pervades all cultures in all times, like flowers blooming in a field. Among these flowers, if I had to choose historical figures to have dinner with, possibly I would select Plotinus or Iambliqus as prominent figures of Neoplatonism, or moving east possibly the zen Chinese patriarch Huineng from the 7th century, whom I adore for his deeply Neoplatonic views; or the 11th century Persian Sufist Suhrawardi; or Pico della Mirandola, one of the fathers of the Rennaissance; or Boehme in 18th century; or Hegel in the 19th century; or Husserl or Jung in the 20th century.

Eating is one of my private pleasures, so possibly ascetic individuals like most of those previously mentioned would not be good company for a dinner; then, if I had to choose someone to really have a good time with, possibly I would choose Jung, with whom I know I would get along very well because of so many common interests in life. I am certainly persuaded that we would enjoy more than one dinner together, addressing topics of common interests combining my physics background with his studies on Hermetism, accompanied with a nice glass of red wine. He was interested in modern physics, and he collaborated with Pauli; some of the dreams he analyses in his Psychology and Alchemy are Pauli’s.

What are you working on, and what do you hope will be the impact of your research?

I am leading a European-Japanese research project, IFMIF/EVEDA, that aims to overcome the pending technological challenges to construct a fusion-relevant neutron source. The project is framed by the Broader Approach Agreement between Europe and Japan in the field of Fusion energy research. IFMIF, the International Fusion Materials Irradiation Facility, is a project whose concept was proposed in the mid-70s, but it demands a high-current linear accelerator, a liquid metal facility and an irradiation facility with unprecedented performances, that frankly were rather science fiction during its first serious attempt with FMIT, the Fusion Materials Irradiation Test facility, in the mid-80s in the US.

Neutrons with suitable flux and energy will be obtained by stripping the neutron out of a deuteron when it impacts a flowing liquid lithium screen. The accelerator needs to run 125 mA at 40 MeV in continuous wave mode (100% duty cycle), something that would have sounded like science fiction early last decade, but that today we know how to do thanks to the on-going development of superconducting cavities for light particles at non-relativistic energies. The liquid metal screen needs to flow at 15 m/s with perfect stability in the beam footprint area to reliably absorb the 5 MW beam power: this has been demonstrated in a full-scale facility constructed and operated in Japan. In turn, since the mid-80s we have known that the degradation of the materials exposed to neutron irradiation is strongly influenced by the temperature of the irradiated materials; we have also demonstrated in Germany that the irradiated specimens can be thermalized within tight margins. We are in the installation and commissioning phase of the Linear IFMIF Prototype Accelerator with our 10 m long RFQ, which will conduct in continuous wave mode a 125 mA beam of deuterons at 9 MeV through superconducting cavities at its last accelerating stage. This will validate the concept of the accelerator, because at such high currents the space charge nonlinear phenomena are more extreme. Basically, at relativistic energies, the Ampere attractive law between adjacent particles cancels magically with the Coulomb repulsive forces among particles, which are in closer proximity the higher the current is.

This facility is indispensable in the world fusion energy roadmaps, because we cannot know the degradation of the materials impacted by the 14 MeV neutrons released in deuterium–tritium fusion reactions without experiments: neither fission neutrons with average energies <2 MeV nor spallation sources with neutrons at all possible energies below the impacting spallating GeV particle can give the needed answers. We need to have the facility in operation next decade if we want to meet the objectives of world fusion roadmaps, because the fusion energy demonstration reactor, DEMO, which is the next step after ITER, demands results from materials irradiated with 14 MeV neutrons with the suitable fluences. 

Which is the development that you would really like to see in the next 10 years?

Certainly, I’d like to see the IFMIF neutron source concept — neutrons at 14 MeV with neutron fluxes 1018 /m2∙s stripped through Li(d,n) nuclear reactions — materialized. There is a European proposal, IFMIF-DONES, a Japanese proposal called A-FNS, and even proposals in China and Korea that are being seriously considered. I wish to see all of them materialized and I think that the need of 14 MeV neutrons is so urgent that there could be a fruitful collaborative operation among all of them.

What Sci-Fi gadget or technology would you most like to have / see come true (and why)?

I have no doubts in this answer, and I guess that the readers would guess… the successful development of nuclear fusion as a source of energy for humankind. I trust that it will come; today we don’t know of alternatives. It is inherently safe, with basically no nuclear waste, and inexhaustible. Renewable energy sources are needed, but they alone cannot cope with human needs. Today we can only dream of harnessing deuterium–tritium nuclear reactions, because the cross sections are high at reachable plasma energies of deuterium and tritium at a few keV, but there are other processes with impressive cross sections at higher energies that could generate energy directly by induction, like p+11B→3 4He, which presents impressive 0.9 barn at 675 keV; unfortunately those temperatures are currently unreachable  (remember that 1 eV equates ~11000 K).

What is your non-scientifically accurate guilty pleasure (could be film/series/book)?

As mentioned before, I am not a supporter of Scientific Materialism. My guilty pleasure, as a scientist, is rather Husserl’s Phenomenology, that is inspired in Hegel’s wonderful book Phenomenology of Spirit, and profoundly linked to Neoplatonism. I would suggest all believers in Scientific Materialism, which are the big majority in our scientific community, to be aware that the fathers of modern physics and mathematics were, sometimes secretly, sometimes openly, devoting most of their research time to philosophical matters fully impregnated by Neoplatonism; in this list I include Kepler, Newton, Leibniz, Descartes, Pascal and Boyle. Quantum physics should make all of us more humble; the shockingly strong links between Neoplatonic ideas and the quantum world should make all of us wonder and get rid of convictions. I particularly adore the non-locality cosmological fact showed by the Einstein–Podolsky–Rosen paradox… at the end of the day, if Lemaitre’s proposal for the origin of the Universe, the ‘Big Bang’ as it was pejoratively named with disbelief by Hoyle, is true as is today generally accepted, the full Universe is, and us as part of it intimately are, enjoying a wonderful quantum entanglement to which our brains can somehow magically connect. Newton, undoubtedly the father of physics, studied alchemy all his life with devotion. I recently read a little book in Spanish, Arcano, written by a lady called Rosa Sinespina that impressed me; unfortunately I guess it is not translated into other languages, but I would recommend its reading, as she addresses physics with a heterodox insight.


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