Nheyo yakajairwa yekuti βzvine simba rakawandaβ yakatangwa kare muzvikamu zvakawanda zvenzanga, kusanganisira sainzi uye tekinoroji. Zvisinei, muzvinhu zvemazuva ano, kushandiswa kunoshanda kweshoko rokuti "duku, asi rine simba" riri kuramba richiwedzera. Izvi zvinoratidzwa zvese mumakomputa, ayo aimbotora kamuri rose, asi zvino anokodzera muchanza chemwana, uye mune inochaja particle accelerators. Hongu, rangarira iyo Large Hadron Collider (LHC), ine mipimo inokatyamadza (26 m muurefu) inoratidzirwa sezvairi muzita rayo? Saka, ichi chatova chinhu chekare maererano nemasayendisiti kubva kuDESY, avo vakagadzira miniature vhezheni yeaccelerator, iyo isiri yakaderera mukuita kune yayo yakazara-saizi yakatangira. Uyezve, iyo mini accelerator yakatoisa rekodhi yenyika itsva pakati pe terahertz accelerators, yakapetwa kaviri simba remaerekitironi akaiswa. Chiyereso chidiki chakagadzirwa sei, ndedzipi misimboti yekushanda kwayo, uye kuedza kunoshanda kwakaratidzei? Chirevo cheboka retsvakurudzo chichatibatsira kuziva pamusoro peizvi. Enda.
Hwaro hwechidzidzo
Sekureva kwaDongfang Zhang nevamwe vaaishanda navo kuDESY (German Electron Synchrotron), vakagadzira mini-accelerator, ultrafast electron sources inoita basa rakakosha zvikuru muhupenyu hwevanhu vemazuva ano. Mazhinji acho anoonekwa mukurapa, kuvandudzwa kwemagetsi uye tsvagiridzo yesainzi. Dambudziko hombe neazvino mutsara accelerators vachishandisa radio frequency oscillators mutengo wavo wakakwira, zvivakwa zvakaomarara, uye inoshamisa mashandisiro emagetsi. Uye zvikanganiso zvakadaro zvinodzikamisa zvakanyanya kuwanikwa kwehunyanzvi hwakadaro kune huwandu hwakawanda hwevashandisi.
Aya matambudziko ari pachena ari kukurudzira kukuru kugadzira zvishandiso zvine saizi uye mashandisiro emagetsi zvisingakonzere kutya.
Pakati pezvinhu zvitsva muindastiri iyi ma terahertz accelerators, ane akati wandei "mabhenefiti":
- Zvinotarisirwa kuti masaisai mapfupi uye mapfupi pulses eterahertz radiation anozowedzera zvakanyanya chikumbaridzo kuparara*, inokonzerwa nemunda, iyo ichawedzera kukurumidza kukurumidza;
Kuparara kwemagetsi* - kuwedzera kwakanyanya kwesimba razvino kana voltage iri pamusoro pekukosha inoshandiswa.
- kuvapo kwenzira dzinoshanda dzekugadzira high-field terahertz mwaranzi inobvumira kuwiriranisa kwemukati pakati pemaerekitironi neminda yekukurudzira;
- Nzira dzeClassical dzinogona kushandiswa kugadzira zvishandiso zvakadaro, asi mutengo wavo, nguva yekugadzira uye saizi ichaderedzwa zvakanyanya.
Masayendisiti anotenda kuti yavo millimeter-scale terahertz accelerator iko kuwirirana pakati pezvakajairwa accelerators aripo parizvino uye ma micro-accelerator ari kugadzirwa, asi ane zvakawanda zvakaipira nekuda kwedikidiki diki.
Vatsvagiri havarambe kuti tekinoroji yekumhanyisa tekinoroji yanga ichikura kwenguva yakati. Nekudaro, mukufunga kwavo, kuchine zvakawanda zvinhu munzvimbo ino izvo zvisina kudzidzwa, kuedzwa kana kuitwa.
Mubasa ravo, ratiri kufunga nhasi, masayendisiti anoratidza kugona kweSTEAM (yakakamurwa terahertz electron accelerator uye manipulator) - yakakamurwa terahertz electron accelerator uye manipulator. STEAM inoita kuti zvikwanise kudzikisa kureba kweyerekitironi danda kusvika sub-picosecond nguva, nekudaro ichipa femtosecond kutonga pamusoro pechikamu chekumhanyisa.
Zvaigoneka kuwana acceleration field ye200 MV/m (MV - megavolt), iyo inotungamira kune rekodhi terahertz acceleration ye> 70 keV (kiloelectronvolt) kubva pakaiswa maerekitironi danda rine simba re55 keV. Nenzira iyi, maerekitironi akakurumidza kusvika ku125 keV akawanikwa.
Chigadzirwa chimiro uye kuita
Mufananidzo Nhamba 1: dhayagiramu yemudziyo uri kudzidza.
Mufananidzo Nhamba 1-2: a - dhayagiramu yezvakagadzirwa 5-layer segmented structure, b - chiyero chekukurumidza kuverengwa uye kutungamirirwa kwe electron propagation.
Electron matanda (55 keV) anogadzirwa kubva electron pfuti* uye vanounzwa mu terahertz STEAM-buncher (beam compressor), mushure mezvo vanopinda muSTEAM-linac (linear accelerator*).
Pfuti yemagetsi* - mudziyo wekugadzira danda remaerekitironi yeinodiwa gadziriso uye simba.
Linear accelerator* - accelerator umo masheji akachaja anopfuura nepakati pechimiro kamwe chete, iyo inosiyanisa mutsara wekumhanyisa kubva kune cyclic imwe (semuenzaniso, iyo LHC).
Midziyo miviri yeSTEAM inogashira terahertz pulses kubva kune imwe iri pedyo-infrared (NIR) laser, iyo inopisawo electron gun's photocathode, zvichikonzera kuwiriranisa kwemukati pakati pemaerekitironi neminda inomhanyisa. Ultraviolet pulses yephotoemission paphotocathode inogadzirwa kuburikidza nematanho maviri anoteedzana GVG* fundamental wavelength yepedyo-infrared light. Izvi zvinoshandura 1020 nm laser pulse kutanga kusvika 510 nm uyezve ku255 nm.
GVG* (optical second harmonic generation) inzira yekubatanidza mafotoni enguva imwechete panguva yekudyidzana nezvinhu zvisina mutsara, izvo zvinotungamira pakuumbwa kwemafotoni matsva ane kaviri simba uye frequency, pamwe nehafu yewavelength.
Iyo yasara yeNIR laser beam yakakamurwa kuita matanda mana, ayo anoshandiswa kugadzira ina-single-cycle terahertz pulses nekugadzira intra-pulse frequency misiyano.
Iwo maviri ma terahertz pulses anobva aendeswa kune yega yega STEAM mudziyo kuburikidza ne symmetrical nyanga zvimiro zvinotungamira terahertz simba munzvimbo yekudyidzana mhiri kwenzira yekuparadzira maerekitironi.
Kana maerekitironi achipinda mumudziyo wega wega weSTEAM, anoburitswa kumagetsi nemagineti zvikamu Lorentz forces*.
Lorentz force* - simba rinoshandiswa neelectromagnetic field pachinhu chakachajwa.
Muchiitiko ichi, nzvimbo yemagetsi ndiyo inokonzera kukurumidza uye kuderedza, uye magnetic field inokonzera lateral deflections.
Mufananidzo #2
Sezvatinoona mumifananidzo 2a ΠΈ 2b, Mukati memudziyo wega wega weSTEAM, matanda eterahertz akakamurwa zvakachinjika nemarata esimbi matete kuita zvidimbu zvakati wandei zvehukobvu hwakasiyana, chimwe nechimwe chichiita senge waveguide, kuendesa chikamu chesimba rose kunzvimbo yekudyidzana. Kune zvakare dielectric mahwendefa mune imwe neimwe layer yekubatanidza nguva yekusvika yeterahertz wave pamberi* nemberi kwemaerekitironi.
Wavefront* - nzvimbo iyo wave yasvika.
Zvose zviri zviviri STEAM zvishandiso zvinoshanda mumagetsi emagetsi, kureva, nenzira yakadai yekuisa simba remagetsi uye kudzvinyirira magnetic field pakati penzvimbo yekubatana.
Muchigadzirwa chekutanga, maerekitironi anoiswa nguva kuti apfuure zero kuyambuka* terahertz munda, uko nguva gradients yemunda wemagetsi inokwidziridzwa uye avhareji munda inoderedzwa.
Zero kuyambuka* - nzvimbo apo pasina makakatanwa.
Ichi chigadziriso chinoita kuti muswe weiyo electron beam ikurumidze uye musoro wayo udzike, zvichiita kuti ballistic longitudinal itarise (2a ΠΈ 2s).
Muchishandiso chechipiri, kuwiriraniswa kwemwaranzi erekitironi neterahertz kunoiswa kuitira kuti bhanhire remaerekitironi rinongosangana nekutenderera kwakashata kwemunda wemagetsi weterahertz. Iyi gadziriso inoguma neti inoenderera kumhanyisa (2b ΠΈ 2d).
Iyo NIR laser ndeye cryogenically cooled Yb:YLF system inogadzira mapurusi emaziso e1.2 ps kureba uye 50 mJ simba pawavelength ye1020 nm uye mwero wekudzokorora we10 Hz. Uye terahertz pulses ine pakati frequency ye0.29 terahertz (nguva ye3.44 ps) inogadzirwa neyakarerekera pulse kumberi nzira.
Kusimbisa STEAM-buncher (beam compressor) chete 2 x 50 nJ ye terahertz simba yakashandiswa, uye STEAM-linac (linear accelerator) yaida 2 x 15 mJ.
Iyo dhayamita yeinopinza uye yekuburitsa maburi ese ari maviri STEAM zvishandiso ndeye 120 microns.
Iyo danda compressor yakagadzirwa nematanda matatu ehurefu hwakaenzana (0 mm), iyo ine fused silica plates (Ο΅r = 225) yehurefu 4.41 uye 0.42 mm kudzora nguva. Hurefu hwakaenzana hwema compressor layers hunoratidza chokwadi chekuti hapana kukurumidza (2s).
Asi mumutsara accelerator hurefu hwakatosiyana - 0.225, 0.225 uye 0.250 mm (+ fused quartz plates 0.42 uye 0.84 mm). Kuwedzera kwehurefu hwechitubu kunotsanangura kuwedzera kwekumhanya kwemaerekitironi panguva yekukwira.
Masayendisiti anocherekedza kuti huwandu hwematanho ndiwo akanangana nekushanda kwechimwe nechimwe chemidziyo miviri iyi. Kuwana mareti epamusoro ekumhanyisa, semuenzaniso, zvingada mamwe maseru uye akasiyana magadzirirwo ehurefu kuti uwedzere kupindirana.
Mibairo yezviedzo zvinoshanda
Chekutanga, vaongorori vanoyeuchidza kuti mune yechinyakare redhiyo frequency accelerators, mhedzisiro yenguva yenguva yeakamisikidzwa erekitironi danda pane zvivakwa zvesimbi inomhanyisa imhaka yeshanduko mundima yemagetsi inowanikwa panguva yekudyidzana kwemaerekitironi akasiyana mukati medanda rinosvika. panguva dzakasiyana. Nekudaro, zvinogona kutarisirwa kuti minda ine ma gradients akakwira uye matanda ane nguva yakareba anotungamira kune yakakura kupararira kwesimba. Majekiseni matanda enguva refu anogonawo kutungamirira kumhando dzepamusoro emittances*.
Emittance* - nzvimbo yechikamu inogarwa nesimbi inomhanyisa yezvimedu zvinochaja.
Panyaya ye terahertz accelerator, nguva yemunda wekunakidzwa inokwana ka200 kupfupika. Saka, kunetsana* munda unotsigirwa uchave wakapetwa ka10.
Simba remunda wemagetsi* - chiratidzo chemunda wemagetsi, yakaenzana nereshiyo yesimba rinoshandiswa kune yakamira point charge yakaiswa pane imwe nzvimbo mumunda kusvika kuhukuru hwekuchaja iyi.
Saka, mune accelerator ye terahertz, magidhidhi emumunda anowanikwa nemaerekitironi anogona kuva maodha akati wandei ehukuru hwepamusoro pane muchina wakajairika. Chiyero chenguva icho munda uno curvature unoonekwa chichava chidiki zvakanyanya. Izvi zvinotevera kubva pane izvi kuti nguva yeiyo yakaunzwa maerekitironi danda ichave neyakajeka mhedzisiro.
Masayendisiti akasarudza kuedza dzidziso idzi mukuita. Kuti vaite izvi, vakaunza maerekitironi matanda enguva dzakasiyana, ayo aidzorwa nekutsikirirwa vachishandisa yekutanga STEAM mudziyo (STEAM-buncher).
Mufananidzo #3
Muchiitiko apo compressor yakanga isina kubatana kune simba, matanda emagetsi (55 keV) ane charge ye ~ 1 fC (femtocoulomb) akapfuura angangoita 300 mm kubva papfuti yeerekitironi kuenda kumutsara wekumhanyisa mudziyo (STEAM-linac). Maerekitironi aya anogona kukura achifurirwa nemauto echaji yechaji kusvika panguva inodarika 1000 fs (femtoseconds).
Panguva iyi, danda remaerekitironi rakatora 60% yehafu-yavelength yendima inomhanyisa pafrequency ye 1,7 ps, zvichikonzera post-acceleration energy spectrum ine peak pa115 keV uye hafu-upamhi hwekugovera simba. kupfuura 60 keV (3a).
Kuenzanisa mibairo iyi neinotarisirwa, mamiriro ekuparadzira maerekitironi kuburikidza nemutsara wekumhanyisa akateedzerwa apo maerekitironi akange asisawirirani ne (kureva, kusawirirana ne) nguva yakakwana yejekiseni. Kuverenga kwemamiriro ezvinhu aya kwakaratidza kuti kuwedzera kwesimba reelektroni kunoenderana nenguva yejekiseni, kusvika kune subpicosecond time scale (3b) Kureva kuti, neyakarongedzerwa, iyo erekitironi ichasangana nehafu-yakazara kutenderera kweterahertz radiation kukwirisa mune yega yega (3s).
Kana maerekitironi akasvika panguva dzakasiyana, anoona kukurumidza kushoma muchikamu chekutanga, izvo zvinoita kuti atore nguva yakareba kufamba nawo. Iyo desynchronization inobva yawedzera muzvikamu zvinotevera, zvichikonzera kuderera kusingadiwe (3d).
Kuti uderedze mhedzisiro yakaipa yekuwedzera kwenguva kweyerekitironi danda, yekutanga STEAM mudziyo wakashanda mukumanikidza mode. Kureba kwetambo ye electron palinac yakagadziridzwa kusvika pakusvika ~350 fs (hafu yehupamhi) nekugadzirisa simba reterahertz rinopihwa kune compressor uye nekuchinja linac kuita hatch mode.4b).
Mufananidzo #4
Iyo shoma shoma yenguva yakatarwa yakatarwa maererano nehurefu hweiyo photocathode UV pulse, yaive ~ 600 fs. Kureba pakati pe compressor uye tambo yakaitawo basa rakakosha, iro rakaganhura kumhanya kwesimba rekukora. Pamwe chete, matanho aya anogonesa femtosecond chaiyo muchikamu chejekiseni chechikamu chekuwedzera.
Mumufananidzo 4a zvinogona kuonekwa kuti kupararira kwesimba kwesimbi yakadzvanywa electron danda mushure mekugadzirisa kukurumidza mumutsara weaccelerator inoderera ne ~ 4 nguva zvichienzaniswa neiyo isina kudzvanywa. Nekuda kwekukurumidza, iyo simba spectrum yesimbi yakamanikidzwa inochinjirwa kune yakakwirira simba, mukupesana neiyo uncompressed danda. Iyo yepamusoro yemagetsi emagetsi mushure mekukurumidza ndeye 115 keV, uye muswe wepamusoro-simba unosvika anenge 125 keV.
Nhamba idzi, maererano nekutaura kwakadzikama kwevesainzi, inyowani yekumhanyisa rekodhi (isati yawedzera kukurumidza yaive 70 keV) mumutsara weterahertz.
Asi kuitira kuderedza kupararira kwesimba (4a), danda rakatopfupika rinofanira kuwanikwa.
Mufananidzo #5
Panyaya yedanda risina kudzvanywa rakaunzwa, kutsamira kweparabolic kwehukuru hwedanda pane ikozvino kunoratidza kuchinjika emittance munzvimbo yakachinjika uye yakatwasuka nzira: Ξ΅x,n = 1.703 mm*mrad uye Ξ΅y,n = 1.491 mm*mrad (5a).
Kudzvanya, zvakare, kwakavandudza kuchinjika emittance ne6 nguva kusvika Ξ΅x,n = 0,285 mm*mrad (yakatwasuka) uye Ξ΅y,n = 0,246 mm*mrad (yakatwasuka).
Zvinokosha kucherechedza kuti dhigirii rekudzikisa emittance yakakura zvakapetwa kaviri kupfuura dhigirii rekuderedzwa kwenguva yedanda, inova chiyero chekusaenderana kwesimba rekudyidzana nenguva iyo maerekitironi anoona kutarisisa kwakasimba uye kudzima simba remagineti panguva yekuwedzera (acceleration).5b ΠΈ 5s).
Mumufananidzo 5b Zvinogona kuonekwa kuti maerekitironi akaunzwa panguva yakafanira anoona hafu-kutenderera kwegetsi kukwira kwemunda. Asi maerekitironi anosvika nguva isati yakwana kana kuti yapera anoona kukurumidza kuderera uye kunyange kuderera zvishoma. Maerekitironi akadaro anopedzisira asisina simba, kana kutaura.
Mamiriro ezvinhu akafanana anoonekwa kana akaiswa kune magnetic field. Ma electrons akabaiwa panguva yakafanira anoona symmetrical huwandu hwezvakanaka uye zvisina kunaka magineti minda. Kana kuiswa kwema electrons kwakaitika nguva yakakwana isati yasvika, ipapo pakanga pane minda yakawanda yakanaka uye shoma shoma. Kana maerekitironi akaunzwa pave paya kupfuura nguva yakakwana, pachava neshoma yakanaka uye yakawanda yakaipa (5s) Uye kutsauka kwakadaro kunotungamirira kune chokwadi chokuti erekitironi inogona kutsauka kuruboshwe, kurudyi, kumusoro kana pasi, zvichienderana nechinzvimbo chayo maererano neaxis, iyo inotungamirira kuwedzera kwekutenderera kunopindirana kunoenderana nekutarisa kana kuderedza danda.
Kuti uwane rumwe ruzivo rwakadzama rwema nuances echidzidzo, ini ndinokurudzira kutarisa ΠΈ kwaari.
Epilogue
Muchidimbu, kuita kwekumhanyisa kuchawedzera kana nguva yesimbi ye electron yakaderedzwa. Mune basa iri, iyo inogoneka danda nguva yakaganhurwa neiyo geometry yekuiswa. Asi, muchirevo, nguva yedanda inogona kusvika pasi pe100 fs.
Masayendisiti anocherechedzawo kuti kunaka kwedanda kunogona kuvandudzwa nekuderedza kureba kwezvikamu uye kuwedzera nhamba yavo. Zvisinei, iyi nzira haina matambudziko, kunyanya kuwedzera kuoma kwekugadzira chigadzirwa.
Iri basa ndiro danho rekutanga rekuwedzera uye kwakadzama kudzidza kwediki vhezheni yemutsara accelerator. Pasinei nekuti iyo yakaedzwa vhezheni iri kutoratidza mhedzisiro yakanakisa, iyo inogona kunzi rekodhi-kutyora, kuchine basa rakawanda rekuita.
Ndatenda nekuverenga, garai muchida kuziva uye muve nevhiki yakanaka vakomana! π
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Source: www.habr.com