Ib pab neeg cov kws tshawb nrhiav coj los ntawm Bob Nagler thiab Thomas Dawb qhia txog qhov kub thiab txias tsis ntev los ntawm kev ceev nrawm ntawm atoms.
Cov ntaub ntawv txhua yam muaj tseeb melting thiab cov ntsiab lus npau npau, tab sis tuaj yeem yog superheated saum lawv kom txog thaum lawv mus txog ib qho kev teeb tsa entropy "ntawm kev loj hlob thiab npau npau.
Thaum pab pawg supermeated khoom kub siab deb dhau nws cov kev txwv tsis pub dhau los rau 19,000 Kelvins, nws muaj qhov tseem ceeb rau cov khoom siv sab sauv yog tias lawv ua kom nrawm nrawm.
Laser Focus lub ntiaj teb: Lub tswv yim twg yog nws rau superheat kub nrog lcls? Dab tsi tshoov nws?
Bob Nagler: Thaum peb npaj tawm mus ua qhov kev sim, peb lub hom phiaj yog los tsim txoj hauv kev tshiab los ntsuas qhov ntsuas kub qeeb. Cov teeb meem no yog ntom yog ib qho khoom siv, tab sis rhuab rau kaum lossis pua pua txhiab degrees Kelvin. Koj pom nws nyob hauv ntiaj teb cov khoom thiab stellar interiors, tab sis thaum peb rov ua dua nyob rau hauv chav kuaj, yeej ntsuas nws qhov kub yog qhov nyuaj.
Peb tau tsim txoj haujlwm no los daws cov kev sib tw no, siv lub ntiaj teb ci ntsa iab tshaj plaws, SLAC National Accelerator's (LCLS), los pab.
Thomas Dawb:Kuv xav hais tias nws yog ib leeg - hma tawm ntawm brilliance tab sis, nyob rau hauv qhov tseeb, lub tswv yim tshwm sim thoob plaws teb. Peb paub tias peb xav tau kev kuaj mob zoo dua, thiab kub ua rau cov khoom siv kuaj cov khoom: ITE} Peb pab neeg ntawm University of University of University, Renac, thiab lwm tus koom tes xav tias yuav ua kom sov li cas thaum tswj nws cov qauv crystalline. Txawm tias ntawm cov huab cua sov hnyav, cov kub latattice pheej ua haujlwm dhau ntawm qhov kev txiav txim siab ntawm cov txheej txheem kev txiav txim. Qhov kev soj ntsuam no hloov pauv qhov ua kom pom tseeb ntawm peb txoj haujlwm. Dab tsi pib ua kev siv zog ua kom tus ntsuas ntsuas cua hloov kho kom zoo dua ntawm superheating thiab qhov tseem ceeb- lub xeev teeb meem nyob rau hauv huab cua.
Lfw: Vim li cas thiaj LBLS?
Dawb:Cov txheej txheem uas peb tsim tsa cov kev sib raug zoo ntawm kev ntes me me hloov nyob rau hauv li cas x {{}}}}} rays tawg tawm atoms hauv cov khoom siv. Tshwj xeeb, me me lub zog hloov qhia daws qhov kub ntawm lub i 50 Nws yuav tsum tsis tsuas yog ib qho kev ci ntsa iab tshwj xeeb ntawm x - rays, tab sis kuj tseem ceeb heev bandwidth. Dawb - Electron lasers zoo li lcs, thiab ob peb lwm tus xws li European xfel, yog muaj peev xwm uas muaj peev xwm xa cov kev sib xyaw no. Lawv tau mus txog ib lub sij hawm ci dua li ib qho tseem ceeb vim tias tsis muaj zog yog qhov tsis muaj ib ob peb lub photons ib qho kev tua.
Nagller:LCLs yog qhov tseem ceeb ib mais -}} Koj sim ua, kuj ua raws li tus ntsuas kub ntev. Yog tias tsis muaj kev sib xyaw ua ke ntawm kev ci ci, coerence, thiab spectral precision, qhov ntsuas no tsuas yog tsis tau.
Lfw: Koj txoj kev sim ua dab tsi?
Nagller: We heated an ultrathin gold foil-just 50-nm thick-using a frequency-doubled Ti:sapphire laser, giving us 400-nm wavelength light with pulse durations around 45 fs. Txawm hais tias tus huab cua sov heev peb tau mus txog, lub laser nws tus kheej tsis yog qhov tseem ceeb los ntawm cov qauv hluav taws xob high-density. Peb tsuas yog siv txog ~ 0.3 MJ ntawm mem tes. Nws txhais tau hais tias cov cua kub ntawm kev sim, kev tsim cov khoom kub, yuav ua luam tawm los ntawm ntau cov lab laser thoob ntiaj teb.
Dawb:Tab sis ntsuas ntsuas kub ntawm yam koj tsim? Nws yog qhov nyuaj. Rau qhov no, koj xav tau cov ultrabright, nqaim - bandwidth, femtosecond x - panas li LCLs thiab ob peb lwm XFels tuaj yeem muab tau. Nws yog dab tsi ua rau qhov kev sim no.
Lfw: Cov ntsiab lus tseem ceeb ntawm qhov kev sim no yog dab tsi? Ib qho kev xav tsis thoob?
Nagller:Rau peb thiab peb daim teb, tus tub rog loj yog qhov tam sim no peb muaj qhov ntsuas kub thiab txias}} The technique opens the door to benchmarking equations of state, validating hydrodynamic simulations, and exploring matter within regimes that were previously out of reach experimentally.
Dawb:Qhov kev xav tsis thoob thaum peb pom tsuas yog deb npaum li cas peb tuaj yeem thawb ib qho khoom ua ntej nws tau muab rau hauv kev tsis sib haum xeeb. Peb cia siab tias lub kub kom yaj ib zaug nws hla ib yam - tab sis nws tsis tau. Lub Crystal lattice tuav ua ke ntawm qhov kub tshaj 14x lub poelting ntau dua 14x lub taw tes melting {4} heev dhau ntawm qhov qauv thermodynamics yuav kwv yees. Nov yog tus '!' Lub sijhawm: tsis yog tsuas yog peb coj qhov kub, tab sis cov kab ke nws tus kheej defied kev cia siab. Hauv kev ua li ntawd, peb pom peb tus kheej tsuas yog daws cov kev sib tw ntawm cov kev tawm dag zog, thawb cov kev txwv tshiab ntawm superheating txog thaum thiab cov khib nyiab npau taws heev.
Lfw: Dab tsi ua nws xav tias nyiam ua tau ib xyoos apades -} Lub tswv yim?
Dawb:Nws yog kev lom zem thiab ntxim nyiam nyiam ua ntej lub tswv yim yuav tsum tau ua kom zoo heev {{0}- Cov tswv yim zoo li no tau thov kom ultrafast, tsis muaj peev xwm ua haujlwm.
Nagller:Nws tsis yog li ntawd txog kev tsis txaus ntseeg ib xyoo lawm - kev tshawb xav li nws tau qhia txog qhov ua kom deb li no- equilibrium superheated xeev. Tus thawj lub moj khaum xav tias lub kaw lus hauv thermal equilibrium, maj mam nce mus rau lub ntsej muag melting, tsis yog ib qho blasted los ntawm ib tug femtosecond laser pulse. Hloov chaw ntawm kev ntxeev siab uas twb muaj lawm, qhov no zoo dua li nqis sab nraud nws tus sau.
Lfw: Qhov kev pom no txhais tau li cas rau superheating?
Nagller:Nws qhia tau hais tias superheated teeb meem nyob rau hauv no tsis muaj tus coj txawv dua li koj tau nthuav tawm cov kev sib txawv no thiab nws yuav nthuav tawm cov kev sib txawv no hauv cov ntsiab lus sib txawv.
Dawb:Thaum kawg, nws qhib cov lus nug ntawm seb puas muaj qhov tseeb txwv rau superheating nyob rau hauv}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}-}}}}}}-}}}}}}}-}}}}}}}-}}}}-}}} Kev khib nyiab zoo tshaj li cov kev kwv yees thermodynamics.
