Piv txwv cov lus nug tham txog cov tshuaj tiv thaiv nuclear (Fission thiab Fusion)
Cov tshuaj tiv thaiv nuclear yog ib qho tseem ceeb heev rau kev txhim kho kev tshawb fawb thiab thev naus laus zis, tshwj xeeb tshaj yog hauv kev lag luam zog. Muaj ob hom tshuaj tiv thaiv nuclear tseem ceeb: fission thiab fusion. Hauv tsab xov xwm no, peb yuav tham txog cov ntsiab lus tseem ceeb, qhov sib txawv, thiab ntau qhov piv txwv ntawm cov teeb meem thiab lawv cov kev daws teeb meem ntsig txog cov tshuaj tiv thaiv nuclear, ob qho tib si fission thiab fusion.
Kev Taw Qhia Txog Fission thiab Fusion Reactions
Kev sib cais yog cov txheej txheem uas lub nucleus loj thiab hnyav, xws li uranium-235 lossis plutonium-239, raug faib ua cov nuclei me dua thiab sib dua. Cov txheej txheem no tso tawm ntau lub zog vim tias qee qhov hnyav ntawm lub nucleus thawj tau hloov mus ua lub zog, raws li Albert Einstein tus qauv nto moo, \(E=mc^2\). Cov tshuaj tiv thaiv kev sib cais yog siv dav hauv cov chaw tsim hluav taws xob nuclear thiab cov riam phom nuclear.
Qhov sib txawv, kev sib xyaw ua ke yog cov txheej txheem uas cov nuclei sib xyaw ua ke los ua cov nuclei hnyav dua. Qhov piv txwv feem ntau ntawm kev sib xyaw ua ke yog kev sib xyaw ntawm cov nuclei hydrogen rau hauv helium, zoo li tshwm sim hauv lub hnub thiab lwm lub hnub qub. Kev sib xyaw ua ke tsim ntau lub zog ib chav tsev ntau dua li kev sib cais thiab yog qhov chaw tseem ceeb ntawm lub zog hauv lub ntiaj teb.
Cov Lus Nug Piv Txwv thiab Kev Sib Tham
Yuav kom nkag siab zoo dua txog ob hom kev tawm tsam nuclear no, cia peb tham txog qee cov lus nug uas feem ntau tshwm sim hauv cov lus qhia txog nuclear physics.
Lo lus nug 1: Kev sib xyaw ua ke ntawm Uranium-235
Ib qho ntawm cov tshuaj tiv thaiv fission feem ntau yog thaum uranium-235 ntes tau ib lub neutron thiab faib ua barium-141 thiab krypton-92, tso peb lub neutron ntxiv. Sau cov qauv rau cov tshuaj tiv thaiv no thiab xam qhov ntau ntawm lub zog uas tso tawm, yog tias lub nuclear mass ntawm uranium-235 yog 235,0439 u, barium-141 yog 140,9144 u, thiab krypton-92 yog 91,9262 u. Lub mass ntawm ib lub neutron yog 1,0087 u.
Kev Sib Tham:
Cov tshuaj tiv thaiv nuclear uas tshwm sim tuaj yeem sau ua:
\[
\text{^{235}_{92}U} + \text{n} \rightarrow \text{^{141}_{56}Ba} + \text{^{92}_{36}Kr} + 3\text{n}
\]
Yuav kom xam tau lub zog uas tso tawm, peb yuav tsum paub qhov hnyav tsis txaus, uas yog qhov sib txawv ntawm qhov hnyav pib thiab qhov hnyav ntawm cov khoom:
1. Qhov hnyav pib = Qhov hnyav ntawm uranium-235 + Qhov hnyav ntawm neutrons = 235,0439 u + 1,0087 u = 236,0526 u
2. Qhov hnyav ntawm cov khoom = Qhov hnyav ntawm barium-141 + Qhov hnyav ntawm krypton-92 + 3 Qhov hnyav ntawm neutron = 140,9144 u + 91,9262 u + 3(1,0087 u) = 235,8607 u
3. Qhov hnyav tsis txaus (Δm) = Qhov hnyav pib - Qhov hnyav khoom = 236,0526 u - 235,8607 u = 0,1919 u
Lub zog uas tso tawm tuaj yeem suav tau los ntawm kev siv cov qauv (E=mc^2), qhov twg 1 u sib npaug rau 931.5 MeV:
\[
\Delta E = \Delta m \times 931.5 \, \text{MeV} = 0.1919 \times 931.5 \, \text{MeV} \approx 178.8 \, \text{MeV}
\]
Yog li, lub zog tso tawm hauv qhov kev sib xyaw fission no yog li 178.8 MeV.
Lo lus nug 2: Kev sib xyaw ua ke ntawm hydrogen
Ua piv txwv ntawm kev sib xyaw ua ke, cia peb xav txog qhov kev sib xyaw ua ke ntawm ob lub deuterium nuclei (\( \text{^2_1H} \)) los tsim ib lub helium-3 nuclei (\( \text{^3_2He} \)) thiab ib lub neutron. Xam lub zog uas tso tawm yog tias qhov hnyav ntawm deuterium yog 2,0141 u, qhov hnyav ntawm helium-3 yog 3,0160 u, thiab qhov hnyav ntawm neutron yog 1,0087 u.
Kev Sib Tham:
Cov tshuaj tiv thaiv nuclear uas tshwm sim tuaj yeem sau ua:
\[
\text{^2_1H} + \text{^2_1H} \rightarrow \text{^3_2He} + \text{n}
\]
Xam qhov hnyav tsis txaus uas tshwm sim hauv cov tshuaj tiv thaiv:
1. Qhov hnyav pib = 2(2,0141 u) = 4,0282 u
2. Qhov hnyav ntawm cov khoom = Qhov hnyav ntawm Helium-3 + Qhov hnyav ntawm Neutron = 3,0160 u + 1,0087 u = 4,0247 u
3. Qhov hnyav tsis txaus (Δm) = Qhov hnyav pib - Qhov hnyav khoom = 4,0282 u - 4,0247 u = 0,0035 u
Lub zog tso tawm tuaj yeem suav tau:
\[
\Delta E = \Delta m \times 931.5 \, \text{MeV} = 0.0035 \times 931.5 \, \text{MeV} \approx 3.26 \, \text{MeV}
\]
Lub zog tso tawm los ntawm qhov kev sib xyaw ua ke no yog li 3.26 MeV.
Kev Sib Piv thiab Daim Ntawv Thov
Los ntawm ob qho piv txwv no, peb tuaj yeem xaus lus tias txawm hais tias cov tshuaj tiv thaiv fusion tsim lub zog tsawg dua me ntsis rau ib qho xwm txheej dua li lub zog tso tawm los ntawm cov tshuaj tiv thaiv fission, qhov zoo tshaj plaws ntawm kev sib xyaw yog nws lub peev xwm muaj zog ntau dua thaum ua tiav ntau, xws li hauv lub tshuab hluav taws xob fusion, uas zoo tagnrho tuaj yeem daws cov teeb meem zog hauv ntiaj teb kom huv si thiab muaj kev nyab xeeb dua.
Cov tshuaj tiv thaiv fission tam sim no siv dav hauv cov chaw tsim hluav taws xob nuclear, tab sis lawv ntsib teeb meem ntsig txog kev nyab xeeb thiab cov khib nyiab radioactive. Lub caij no, cov tshuaj tiv thaiv fusion, lub hauv paus ntawm lub hnub ci thiab lub zog hnub qub, tab tom tsim kho, nrog rau cov haujlwm zoo li ITER hauv Fabkis lub hom phiaj los qhia txog kev ua tau zoo ntawm nuclear fusion ua lub zog huv yav tom ntej.
Xaus
Kev nkag siab txog cov tshuaj tiv thaiv nuclear, ob qho tib si fission thiab fusion, yog qhov tseem ceeb heev rau hauv cov ntsiab lus ntawm kev txhim kho thev naus laus zis thiab kev tshawb fawb. Ntxiv mus, qhov kev paub no muab kev nkag siab tob dua txog seb lub ntiaj teb ua haujlwm li cas thiab nws cov kev siv tau hauv kev muab cov peev txheej hluav taws xob ruaj khov. Hauv kev kawm txog cov tshuaj tiv thaiv nuclear, cov teeb meem kev xyaum zoo li cov uas tau tham saum toj no pab ua kom peb nkag siab tob txog cov tswv yim thiab kev siv ntawm lub zog nuclear.
