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INDUSTRY
December 2023 ESRFnews
T he ESRF vacuum group is helping a start-up develop key technology for
its nuclear fusion reactor.
Over the past 15 years or so, many
start-ups have set themselves a goal
that has so far eluded multi-billion-
dollar projects: the generation of
useful energy by nuclear fusion. One
of these companies is Renaissance
Fusion. Established in 2020 in
Grenoble, France, Renaissance Fusion
has been collaborating with the ESRF
in the technical development of a
“stellarator”.
The stellarator is a mature concept.
In fact, it was invented in the early
1950s, several years before the
tokamak – an alternative concept
that forms the basic design of most
large-scale fusion projects, including
the international ITER facility under
construction in the south of France.
Both concepts use magnetic fields
to confine a plasma – the hot gas
of charged reactants – in the shape
of a doughnut, or torus; the main
difference is that a stellarator induces
fusion reactions thanks to a complex,
helical-shape magnetic field, whereas
in the tokamak the plasma is heated
by a current generated by a central coil
in a pulsed mode of operation. The
stellarator has theoretical advantages
over the tokamak – it is a steady-
state machine not subject to plasma
instabilities – but historically its coils
have had more complicated shapes,
and have needed to be aligned very
accurately to achieve good plasma
performance. Renaissance Fusion is
striving to change that, with its own
unique technologies.
One of these concerns the
manufacture of wide high
temperature superconductors
HTSs which can generate very
high magnetic fields and reduce
the size of reactors Commercial
HTSs come in tapes that are
12 mm wide making them time
consuming and expensive to apply
to other components Engineers
and scientists at Renaissance Fusion
are therefore developing methods
of manufacturing HTS sheets that
are one metre wide which can then
be cut by laser to any precise shape
required, rather like how modern
electronic circuits are manufactured.
This demands bigger physical
and chemical vapour deposition
machines, which must sustain high
vacuum levels before deposition starts
and manage high gas flows once it is
proceeding.
This is where the ESRF comes in.
Since last year, with support from
the EU-funded TamaTA-INNOV
synchrotron access programme,
Cristian Maccarrone and the rest of
the ESRFs vacuum group have been
working with Renaissance Fusion
on calculations measurements and
defining vacuum system components
to help the companys engineers
design new physical and chemical
vapour deposition machines as well
as a vacuum vessel and a liquidmetals
experiment For each of these three
pillars of Renaissance Fusions
stellarator a very good vacuum is
relevant We dont have the vacuum
expertise that Cristian has so his
contribution has been really valuable
Fusing expertise
R E I N I S B A R A N O V S K I S / R E N A I S S A N C E F U S I O N
says Carlo Sborchia, head of magnets,
vacuum and cryogenics at the company.
“We hope to continue collaborating
with the ESRF in future experiments to
develop our stellarator design.”
Renaissance Fusion are developing
their method of laser-cutting very
large sheets of HTS, which should
enable the creation of current patterns
that deliver incredibly precise and
powerful magnetic fields to make a
stellarator easy to build. Large HTS
sheets could also deliver benefits
outside of fusion by making it
easier and cheaper to manufacture
HTS power cables and energy
storage systems for example In its
collaboration the ESRF will help
make all that happen and its name
brings distinction too The ESRF is
a very prestigious research centre so
its great to be associated with it says
Domenico DAndrea Renaissance
Fusions head of business development
and sales
Jon Cartwright
Rattena Tang in Renaissance Fusion’s HTS team works on a roll-to-roll vapour-deposition test machine.
“The ESRF
is a very
prestigious
research
centre, so it’s
great to be
associated
with it”