I3^_ KHOA HOC VA CONG NGHE MO ^ NGHllN CIJU KHn NRNG LflM SUV GIRAA , SONG XUNG KiCH LAN TRUYEN TRONG KHONG KHI ' KHI NO LU'ONG THUOC BANG KHI HELif PGS.TS DAM TRQNG THANG Hgc Vien Ky thupt quan sw ^ • ^ iai phdp ldm hgn chl, suy giam hay triet tieu f " ^ sdng xung kieh lan truyin khdng Id " ^ ^ mpt vln d l rat duoe quan tam edng dc an todn n l , dae bigt vd'i cdc vg nd khdng chi Theo iy thuyet nd cae mdi trudng khdc ihau, sdng n l truyin tu mdi tmd'ng mgt dp eao Jang mgt dg thdp thi cud-ng dp sdng no se bj suy jiam Xult phat tu dgc tinh ndy, bai bao da trinh 3dy kit qua nghien euu budc dau v l su dgng ihg Heli (He) d l lam suy giam sdng xung kieh, md (hdng lam phdt sinh manh vang Ting quan Trong thyc tiln nd phd huy ddt da, pha vy (It eau hay dli tuyng khac bdng luyng n l dat igodi, sdng xung kich hinh thdnh vd lan truyin Tong khdng ed gid tri Id'n gap nhilu lan so vdi Tudng hyp luyng nd duyc ehdn vat thl Sdng xung kieh Id mgt tac nhan chinh gay nguy l i i m eho ngudi vd pha buy mdi trudng xung Huanh D I giam cudng dp sdng xung kieh ian [ruyln khdng khi, cong tdc nd ndi chung ihdng thudng dp dgng cdng nghg nd vi sai hay idng eudng bua Tuy nhign pha buy ddt da, ng minh ring [2], [4], [5]: sdng n l lan tmyln CfiNG NGHIEP MO, sti 4-2015 | tip mdi trudng ndy sang mdi trudng khae, thi^xa^ sy phan xg, khue xg sdng; dgc biet tnjyln|H mdi trudng ed mgt dp va dd ben kem hon thi se Idm phdn sdng n l ; sdng n l truyin ^ da, di qua khe nut se lam suy giam hay triet t i ^ sdng nd; higu ung da duyc i>ng dgng trom phuong phdp n l tgo bidn tgo khe trudc, V i « cd thl nhgn thay rang su dgng nhe Heli d l \m suy giam cudng dp sdng xung kich Id mgt h\t&^ nghien euu cd nghTa khoa hpe va thye tien Phan tich co" sd ly thuylt v l s y lan truyin cua song xung kich khong Khi no khdng khi, cDng vdi qua trinh vSng cua san pham no Id sy hlnh thdnh vd lan truy^ cua sdng xung kich khdng Sau kich nl t i i thdi iuong nd hlnh cau, san phim n l hinh vd y thdi dilm dau tien nd ndm bat ddng thl tlcti lyyng no Khi dd ldp khdng ndm sat luyng nfl cung d trgng thdi bat ddng, nhung vdi mgt dp su^, nhigt dp nhd hon rat nhilu so vdi dp suit, nhiet dO san pham n l Sau dd tren b l mgt phSn chia san phdm nd vd khdng bao quanh, du'di tde dgng ciia dp suat du rdt ldn lam eho nd bat 6k chuyin dpng theo hudng mdi trudng ben ngoai, Dau tign tham gia vdo chuyin dpng la cSc ldp san phdm n l , ldp khdng khf tryc tilp tilp giSf vdi b l mgt phan cdch Sau dd keo theo sy chuyfe dpng cua cde Idp san phdm n l a sau hon va c^( ldp khdng y xa hon B l mgt phan chi^cach? san phdm no dang tham gia vdo chuyin dpng, vd cdc hgt san phdm n l cdn d trgng thai finh, mj chuyin dpng sdu vdo tam n l vdi toe dd khdng 3fi ao, bdng tic dd am san pham no gpi la m3 sdng ddu hg dp Vi v$y dp suit vd mdt d | sai pham_ n l qua mdt se giam Khi b l mgt n& ehuyln dgng din tdm cua luyng nd thi t i t ca c& hgt san phim nd tham gia vao chuyin ddng KHOA HOC VA CANG NGHE MO Be mat phan chia giaa viing kh6ng i