Newsgroup: it.discussioni.energie-alternative
Titolo: Giurino giurello Barabaschi di ITER promette date realistiche


 
e ora dopo la debacle per problemi di saldatura, il nuovo direttore
ha promesso di indicare date realistiche per la costruzione di ITER.
 
Ricordo che nel 2016, il "primo plasma" avrebbe dovuto ottenersi
per il 2025, ma Barabaschi ha detto alla 29-esima conferenza della
IAEA sulla Energia da Fusione che non c'e' modo di arrivarci.
 
Per ora, e' certo, che il nuovo piano di costruzione indichera'
una data dopo il 2025 per il "primo plasma" dell'ITER (e in
quanto alla "prima accensione" ... aspetta e spera).
 
Dunque, su 19 bobine toroidale, 17 sono gia' sul posto e le altre
due sono gia' state fabbricate. Poi ci sono 6 bobine "poloidali"
(la piu' grande ha 24 metri di diametro, con una massa di 400
tonnellate), due sono installate (quali ?) e una e' gia' pronta
nel sito, altre due dovrebbero essere completate a fine anno
(manca una ? sono cinque quelle descritte).
 
Il problema e' il "contenitore a vuoto" ... e ci sono anche problemi
"burocratici" con l'ASN, l'autorita' di sicurezza nucleare francese,
ma visti i tempi, non c'e' da pensare che avra' influenza sulle
scadenze.
 
Hanno anche deciso di cambiare il materiale del primo strato del
muro (quello interno), da berillio si passa al tungsteno.
 
Abbiamo anche la descrizione di "cosa dovrebbe fare/dimostrare" ITER:
 
"The goal of ITER is to operate at 500 MW (for at least 400 seconds
 continuously) with 50 MW of plasma heating power input. It appears
 that an additional 300 MW of electricity input may be required in
 operation."
 
NB: ITER non produrra energia elettrica (non e' previsto il
collegamento ad un generatore di vapore e turbina a vapore-generatore).
 
Meta' del progetto e' finanziato dalla UE insieme a Svizzera.
L'altra meta' in parti uguali da Cina, India, Giappone, Corea del Sud,
Russia e USA. Russia ?
 


 
Da un articolo del New York Time (dietro Paywall):
 
Il numero chiave raggiunto questo luglio: 3,88 MJ
 
"The experiment in December generated a whirlwind of accolades when it
produced about three megajoules of energy — equivalent to about 1.5
pounds of TNT, or about 1.5 times the energy of the incoming lasers. It
was the first time that a fusion reaction in a laboratory setting produced
more energy than it took to start the reaction.
The July experiment was essentially identical to the December
one. “We expected a similar yield,” Dr. Town said. “On the order
of three megajoules.”
The actual output was 3.88 megajoules. The
better-than-predicted result indicates that with a few tweaks, laser
fusion can become markedly more efficient. But minuscule variations
could yield fusion duds as well.
A fusion experiment in June, just a month earlier, was also predicted to
produce about three megajoules, but it generated only between 1.6 and
1.7 megajoules, Dr. Town said.
A more recent attempt this month, as part of efforts to maintain
nuclear weapons without underground nuclear tests, yielded slightly
more than two megajoules, breaking even with the laser energy.
“It was a little bit surprising that
we did not achieve ignition on all of them,” Dr. Town said.
Why It Matters: Much more to learn.
Analyzing the results, the Livermore scientists now think they better
understand what is going on. For one, the 192
lasers are not perfect. “There are some variations every time you shoot
the laser,” Dr. Town said. Instead
of laser energy arriving perfectly balanced to compress the hydrogen
fuel capsule, a slight imbalance nudges the capsule off in one
direction. Some of the energy is lost, and the inward implosion does
not heat the hydrogen as much. There
are also slight variations in the fuel capsules that affect the fusion
reactions. Computer simulations now indicate there can be a wide range
in the output energy. “It could fall
as low as 1.4 megajoules,” Dr. Town said. “And if the stars align and
everything works perfectly, it could get up to seven megajoules.”
What Happens Next: Upgrading and optimizing the experiment.
Siegfried Glenzer, a scientist at the SLAC National Accelerator
Laboratory in Menlo Park, Calif., who led the initial fusion experiments
at the Livermore facility years ago, said of the July advance, “The
fact that the gain has gone up on the last shot is encouraging news and
shows that the current implosions are not yet fully optimized.”
A new series of experiments is about to begin
at the National Ignition Facility as it aims to generate higher fusion
yields more consistently. The energy of the facility’s lasers is being
upgraded to 2.2 megajoules from 2.05. The latest advances occurred after
the last upgrade from 1.9 megajoules. Additional energy is expected to
lead to further improvements.
“If you can couple effectively more energy to the hot spot, you should get
more yield,” Dr. Town said. “You can do that by having a bigger hammer.
 


 
UK-based company Pulsar Fusion has started to construct what it says
is the largest practical nuclear fusion rocket engine ever built, and
intends to fire it in 2027.
 
According to Pulsar Fusion, which was founded in 2011 and is based in
Bletchley, Oxfordshire, its fusion-powered rocket has the potential to
travel as fast as 500,000mph (805,000km/h) and reach Mars in 30 days.
 
Engineers at the company are assembling an 8m (26ft) wide fusion chamber
capable of containing a plasma several hundred- million degrees centigrade
hot when it is fired up in 2027 — temperatures hotter than the Sun.
 
Dr James Lambert, director of operations at Pulsar Fusion said, “The
difficulty is learning how to hold and confine the super-hot plasma
within an electromagnetic field.
 
“The plasma behaves like a weather system in terms of being incredibly
hard to predict using conventional techniques. Scientists have not been
able to control the turbulent plasma as it is heated to hundreds of
millions of degrees and the reaction simply stops.
 
“Scientists can get to fusion temperatures, as recently demonstrated
at the Lawrence Livermore laboratory in 2022, and this will be achieved
again more often going forward, but small improvements can dramatically
improve the results in our favor.”
 
Energy from the process of nuclear fusion, as opposed to atom-splitting
fission, has been seen as a holy grail by engineers for decades for
power generation because its byproducts are not as dangerous. However,
despite significant investment and some breakthroughs a self-sustaining,
contained fusion reaction has proved elusive and most experts agree a
nuclear fusion power station is still decades away.
 
Pulsar believes that recent advances in machine learning techniques will
enable faster progress in understanding the way super-hot plasma behaves
and enable the development of its Direct Fusion Drive (DFD) rocket.
 
The company is partnering with Princeton Satellite Systems and using
data from the World record holding PFRC-2 (Princeton field-reversed
configuration) reactor to create computer simulations which predict
how super-hot plasma behaves under electromagnetic confinement. These
simulations will be used to guide and improve the design of the rocket
engine prototype.
 
Richard Dinan CEO of Pulsar said, “Our current satellite engines
we make today at Pulsar, produce up to 25 miles per second in exhaust
speeds. We hope to achieve over 10 times that with fusion.
 
“If the Pulsar rocket test can achieve fusion temperatures at its
demonstration to Aerospace partners in 2027, then the technology has the
potential to half mission times to Mars, reduce flight time to Saturn from
8 years to 2 and ultimately empower humanity to leave our solar system.