Dear AAPPS-DPP members
Thank you for coming AAPPS-DPP 2017 in Chendgdu.
We had very nice talk by Prof. Michael Bonitz on Strongly coupled plasma.
I found an article on metallic hydrogen in Physics world as attached.
See Prof. S. Ichimaru’s RMPP Chandrasekhar Lecture athttps://link.springer.com/journal/41614/1/1/page/1
We also have Obituary : Predhiman Krishan Kaw as well.
Prof. Rikizo Hatakeyama’s Nanocarbon materials fabricated using plasmas is also
published on line.

Dr. M. Kikuchi
Chairman, AAPPS-DPP
Chairman, Reviews of Modern Plasma Physics(http://www.springer.com/physics/atomic,+molecular,+optical+%26+plasma+physics/journal/41614)
Guest Professor, Osaka Univ., Japan
Visiting professor, Southwestern Institute of Physics, China
Visiting professor, Modern Physics Institute, Fudan University, China
QST(National Institutes for Quantum and Radiological Science and Technology), JapanTel:
81-29-270-7294
Fax:
81-29-270-7462
e-mail: kikuchi.mitsuru@qst.go.jp
311-0193, Muko-yama 801-1, Naka-city, Ibaraki, Japan

Feature: Meta 11ic hyd rogen

Physlcswo"d.com

田﹂豐一一のU叫拐一で亡田m舟一0愽晋田"495 Gpa^

4‑"f4'父メ'Sh州 Usyour metal
One ofthe rarest metals in the universe, meta11ic hydrogen could solve many energy problems ‑ but hasi廿ina11y been isolated in the lab? on cart r晤httries to sort out claim from counter・claim
Scientists aren't immune to the a11Ure of rare met・

For over a century physicists have sought meta11ic

als.1Saac Newton's interestin alchemy is weⅡ docu・ hydrogen. xvithin the past year, however, physicists
mented: when the natural philosopher wasn'tlaying Isaac silvera and Ranga Dias (pictured above) at

the groundwork for much of modern physics he wasOften secretively, obsessively, a杜empting to turn lead

into gold. These days, physicists are hoping to turna humble elementinto somethingyet more precious.

HydrogenisthelightestofaⅡ atoms, notto mention

based in Brist01, UK,

HarvarduniversityinMassachusetts, US, daimthey jcartⅧ晤ht.CO.uk
have fina11y made it, by squeezing hydrogen inside a
diamond anvilce11to pressures of nearly five mi11ion
atmospheres.1S it for real?" 1f it is true, it is a great
achievement, fuHi11ing a long search for the atomic
Phase of hydrogen," says David ceperley, a theoristat the university of 111inois urbana‑champaign inthe most abundant, accounting forthree・quarters ofaⅡ the universe's normal matter. As we commonly
know it, hydrogen is a molecular gas ‑ C010urless, the us."However, there is deep scepticism in theOdourless, mostly harmless and, some might say, Community abouttheir experiment."
rather dUⅡ. But under extreme pressure, hydrogen

Wi11Supposedly turn into one ofthe rarest metals in Early searches
the universe, one that is natura11y non‑existent here Subjecting hydrogen to extreme conditions is cer・On Earth and perhaps only present in the under・ tainly nothing new.1t was on the cusp of the 20thWorlds ofgasgiants, such as Jupiter. The metalis cov・ Century that the British scientist James Dewar first
eted notjust for its rarity, but also because it could Cooled hydrogen untilit turned solid, at tempera・turn outto be a stable room・temperature supercon・ tures of less than 14K. Around this time, chemists
ductor, and therefore go a great way to solving the Were also mU11ing over the element's position in
the periodic table. situated at the top of a column
World's energy problems.
Physlcs wo"d october 2017

Jon cartwr1武htis afreelancejournalist

Feature: MetaⅡic hydrogen

Physlcswo"d.com

X入lhile aⅡ this phase・mapping has been taking
Place, theorists have been coming up with rewards
for isolating the elusive metal.1n the late 1960S,Physicist NeilAshcroft at corneⅡ University in New
York, US, predicted that solid meta11ic hydrogen

I Goin琴 throU岩h a phase︑一一巳Φ三コで﹂里﹄"モ伺﹂Φ三一仂﹂一2000

Could be a high・temperature superconductor; and in

the past decade, other theorists have suggested that1500

the criticaltemperature for such a superconductor

Iiquid全)Φ岩超﹂豊EΦ一●り﹂コ0のCould be above room temperature, unlike any other1川Uid metal

known to date.

Another use that silvera and others have recendy

Speculated is that the substance could serve as arocket fuel. According to their calculations, solid
metaⅡic hydrogen's specific impulse ‑ the standard
measure ofa propeⅡant‑would be more than three

1000

and ahaHtimesgreaterthanthemixof Hquid hydro、
500
Solid
me始1?

0100200300

400

Pressure (Gpa)

Hydrogen is a gas under ordinary atmospherjc conditions, which on this chartis too sma11 areeion to be resolved. under high pressures, the elementforms a liquid when very hot, or anon・metal"c solid at moderate temperatures. The non・meta11ic solid region has four phases,
described in the main article,in which hydr0且印 is arra嘔ed in various close.packed
Structures. since 1935 theory has predicted that hydrogen can also form a meta11ic solid
Under very high pressures, which experimentalists have been strivingto produce eversjnce.

gen and oxygen traditiona11y used to fuel rockets,
a110wing far more ambitious space travel. Granted,

Creating the conditions for solid meta11ic hydrogenin a fueltank would not be easy, but calculationS 血the early 1970s by physicists at the soviet union'S
IV Kurchatov lnstitute of Atomic Energy in MOS、
Cow suggested that solid metaⅡic hydrogen could
actua11y be metastable at room temperature andPressure: once created, it would stay a metal even
When the pressure is released.
Not that such applications have driven silvera in
his quest for the metal."1've always been interested

in very chaⅡenging problems," he says."And in thehigh・pressure research community, metaⅡic hydro・gen was always considered to be one ofthe greatest

Of alkali metals, hydrogen ought to form a metal ChaⅡenges that existed." He began his search in theitself, given the right conditions. Those conditions

Were first calculated in 1935 by the Hungarian、born physicist Eugene X入ligner and the us physicist
Hi11ard BeⅡ Huntington, who predicted that attem、Peratures dose to absolute zero, and at pressures
Of about 250ooo atmospheres (25Gpa), hydrogen1970s while a professor atthe university ofAmster、

damintheNetherlands, andthoughothertopicshave
OccasionaⅡy diverted him ‑ in 1979, for example, heand his Amsterdam c0ⅡeagueJook walraven madehydrogen into the first quantum gas,the precursortoa Bose‑Einstein condensate‑metaⅡichydrogen has
atoms oughtto become so dosely packed thattheir always been atthe forefront ofhis mind.
For most scientists in the field there is little doubt
electron douds overlap, asin a metal.

Wigner and Huntington had fired the starting thatthe state exists.1ndeed,itis believed that hydro、Pistolin the search for meta11ic hydrogen, but their gen in the highly compressed cores of the larger

Prediction was optimistic. X入lith the invention of the gas giants, such as Jupiter, must be metaⅡic ‑ albeit
diamond anvilceⅡ atthe NationalBureau ofstand、 Probably liquid rather than solid in form ‑ in orderards @ow the Nationa11nstitute of standards and to generate their observed magnetic fields."Eve・Techn010gy, or NIST) in the late 1950S, high pres・ ryone believed that if you got hydrogen to a highSures suddenly became routinely accessible; and by enough density, which means a high enough pres・the 1970S,theywere topping looGpa‑yetforhydro・ Sure," says silvera,"thatit would become metaⅡic."
gen, there was no sign of a metaltransition.

Quite where the transition lay, however, no‑one was

Sti11, hydrogen's phase diagram could be mapped Sure, and rampingup the pressure to find out has not
With ever greater darity (figure D. The element is been easy.
always a solid at high pressure and at moderate tem、Diamond anvil ce11S consist of a pair of diamonds

Peratures, but takes on distinct phases depending that have had their points polished down to a sma11
On just how high the pressure is. phase lis a dose、 aat tip known as a culet. The hydrogen sample isPacked structure in which the molecular angles are Compressed between the two culets within a con、disordered. phase 11 is a similar structure but with taining gasket, having been loaded in gas or Hquid
Some degree of orientational order. phase 111 is form. But if you turn the pressure up too high, thebelieved to be a structure in which the strength of diamonds themselves are liable to fail.
the hydrogen‑hydrogen bonds turns so weak that
About a decade ago, however, several experi・
the hydrogen can be considered partly atomic, not mental groups found ways of boosting the pres・molecular.1n phase lv, some evidence suggests a Sures of hydrogen within diamond anvil ce11S from
Portion ofthe hydrogen molecules form planar, gra・ the long・held maximum of about 20OGpa to nearly
Phene・esque sheets. Beyond those phases? Meta11ic 40OGpa ‑ higherthan the centre ofthe Earth ‑ buthydrogen ‑ possibly.
this appeared to be another plateau. unfortunately,
Phy$ics wo"d october 2017

Feature: M eta 11ic hyd rogen

Physlcswo"d.com

2 Lens・eye vlew
巴Φ三一のり舟拐一で区舟袷一om叫こ舟化

Taken usinga smartphone camera,these photographsshowthe view down a microscope ofRanea Dias and lsaac silvera'ssample, underincreasing pressure from leftto right. Dias and silvera descrjbe these images as showing (1eft) transparent H2,(middle) opaque H2 and(right) reflective H. The duo believe thatthe far・r培huma旦e shows the first lab、created meta11ic solid hydrogen. However,血is claim is at
Presentcontroversial amongthe research community.

attaining these pressures is an art as much as a sci・ the cMos camera on a suitable microscope. Fitting

ence, as it is not always clear what causes the dia・ these measurements at several wavelengths to themondsto break.

WeⅡ、established Drude model of electrical conduc・tion, the researchers found thatthere was the sameLab elation

density ofelectron carriers asthe density of atomsin

In recent years, silvera and Dias, his postgraduate the system, a ha11mark of a metal(scieπCe lo.1126/Student, have been developing ways to deliver yet Science.aa11579).
Ihe celebration was perhaps shorter lived thanhigherpressures. F電Uring that defects are one ofthe
Causes ofpremature diamond failure,they etch away Silvera and Dias would have liked. Minus a laser,
the surface of their synthetic diamonds with an ion they were only able to roughly estimate the pressure
gun,to remove any layers ofcarbon atomsthat have On their hydrogen indirecdy via strain gauges on
been accidentaⅡy gouged during the culet・polishing the ceⅡ:495Gpa, give or take 5‑10%. others, theyProcess. They have also gotinto the habit of coating knew, would want a more reliable reading, particu・

Iarly given the fact that it was substantia11y greater
Sapphirewhenitisagemstone‑whichshouldprevent than most groups report. Tentatively,then, the Har・
any hydrogen diffusing into and embrittling them. Vard pair set up a weak, half・mi11iwattlaser to take
Fina11y, they avoid any continuous i11Umination with a reading."圦le turned the laser on: one of the dia・
Iaser lightto study the experiments in progress, as it monds broke," says silvera."catastrophica11y‑there
is believed to be a trigger for failure."That turned Wasnoth血gleftbut powder,1ike flour." The precious

their diamonds with alumina ‑ otherwise known asmetalhad apparendy slipped away.
Outto be important," silvera reca11S.
So it was thatin october last year, working in hisOffice, silvera was intenupted by an excited Dias at Scepticalresponse
his door, and the pair rushed back to the lab where Many other experimentalists, however, believe it
the postdoc had been stepping up the pressure in Was notthere in the first place. Eugene Gregoryanz
their latest ceⅡ, at temperatures lower than 83K. Ofthe university of Edinburgh in the uK has been
Seen through an optical microscope, the hydrogen One of the most vocal critics: on a scale of l t010,
Sample was n010nger matt black, but had a metaⅡic Where lo is the most sceptical, he places himself atIustre. Both silvera and Dias knew whatthis meant

11. He says silvera and Dias' paper, in which they

and, having nothing better to hand, took pictures
Ofthe sample with an iphone."people often askedme, how are you going to know ifyou've got meta11ic

Peop e often asked me, how are youhydrogen?" says silvera.'And lwould say: by a11thegoing to know if you've got meta11ic
hydrogen? And l would say: by a11thethat its Dc conductivity stays finite as its tempera・ ye11ing and screaming coming out ofture is broughtto absolute zero‑ameasurementthat

yeⅡing and screaming coming out ofthe laboratory
Mywhole group wasvery excited."
According to silvera,thereare twowaysto demon・Strate that a substance is meta11ic. The firstisto showrequires four electrica11eads to remain in contact
With the microscopic sample inside the ce11 as, withrising pressure,its volume diminisheS 15・fold. Hav・
ing no apparatus to do that, the researchers instead
Opted forthe secondmethod: Ac conductivity,which
manifests as reflectance and can be measured via
Physicsworld october 2017

the laboratory