Introduction to Accelerators

Transcription

1 Intoduction to Acceleatos F. Willeke, DESY MHE Basic Physics of Paticle Acceleation Powe Souces fo Acceleation and Acceleating Stuctues Linea Acceleatos Motion of Paticles in a Magnetic Field Cicula Acceleatos Supeconducting Magnets Acceleatos at DESY

2 Intoduction An enomous eolution led fom the fist table top acceleatos in the 19-ies to the lage spectum of instuments fo science and technology. This includes small industially poduced linea acceleatos, acceleatos fo cance teatment, and lage facilities of many kilometes in size used to delie beams fo fundamental physics Rolf Rolf Wideoe s fist fist acceleation tube tube Aial View of LEP/LHC

3 Basic Fomulae and Notation Basic Fomulae and Notation ( E) B e F F p dt d + Equation of motion Loentz Foce Relatiistic Fomulae 1 / γ β γ γ β β γ γ c m c m p m c c m c p E c m m

4 Maxwell s Equations Maxwell s Equations + B D B t E D t J H ρ + S S V s s B da x d D da B da t dse D t J da dsh ) ( 3 ρ

5 Acceleation Enegy Gain dp e ε( t) dt ε ( t) ε sin( ω t) d dt d γ ( t) ( t) c s( t) c γ γ γ 1 e ε ( t) 1 dt m c e m c e ε mcω t dτ e m c γ ( t) γ ( t) ε ( t) ε( t) ds ( 1 cos( ω t) ) + ( βγ ) 1 γ ( τ ) γ ( τ ) Enegy Gain/ Rest Enegy γ t j, γ i e-enegy Gain in an Accel. Stuctue ε(t) Input Momentum Electical Fie p i kevc ε 1MVm 1 Input Phase φ.48( π) Fequency ω π Length 5MHz s m.3m s j, i s m

6 Caity Resonatos 1 1 t B c B t E c E E E Solution in cylindical coodinates ) ( ) exp( ) ( ), ( R k J c k t k J E t E n n n n n n zn ω ω B Acceleation Mode: TM 1 R d

7 Powe Souces and Acceleating Stuctues Maste Oscillato Amplifie Tube Input Couple B Acceleating Stuctue (Caity) ε Suppesso Gid + Plate Anode P Sceen Acceleato Gid Powe Tube schematically Contol Gid Cathode Heate Filament

8 Powe Souces and Acceleating Stuctues Klyston, most common souce of RF powe fo paticle acceleation Boile The electon gun poduces a flow of electons. The bunching caities egulate the speed of the electons so that they aie in bunches at the output caity. The bunches of electons excite micowaes in the output caity of the klyston. The micowaes flow into the waeguide, which tanspots them to the acceleato. The electons ae absobed in the beam stop. Output Caity Input Caity Anode

9 Linea Acceleatos Low Enegy Hadon Acceleation: (β<1) Dift Tube Linac (Alaez LINAC) Dift tubes with quadupole magnets fo focusing E l b l b l b Resonato Tank 3-D sketch

10 epton High Enegy Linacs Focussing Quadupole magnets Acceleating Stuctue φ c PaticleBeam RF Powe Flow Input Couple RF Pulse Compesso Pulsed Klyston Dump Modulato HV Pulse Geneato Tigge HV Supply

11 Supe Conducting Multi-Cell Nb Caity Resonato fo the TESLA Linea Collide

12 Basics of Cicula Acceleatos Magnetic field B F Deflecting foce keeps paticles on a cicula tajectoy F e x B ε Electic field fo Acceleation and Focusing ( Ee dt ε)

13 Bending Radius Bending Radius 1) ( ) ( ) ( t i L t i L y x z y x L L e i e i dt d i m eb i i dt d ω ω ω ξ η η ξ ξ ξ ω ξ γ z x y eb dt dp z z L x y L L y L L x L L x L L y eb p eb m t t y y t t x x γ ω ρ ω ω ω ω ω ω ω ω ) sin( 1) ) (cos( ) sin( 1) ) (cos( y i x i y x + + η ξ γ ω m eb z L x y z B z z y x eb dt dp ) sin( ) cos( t y t x L L ω ρ ω ρ y x y x ρ ρ Lamo Fequency ρ p / eb z ρ p / eb z

14 Weak Focussing R R? fr /l R

15 ε(t) Cycloton fo a classical paticle, (g~1 )the Lamo fequency w L eb /(m γ)is independent of enegy Cycloton suited fo acceleation of heay paticles such as potons o ions B DEE Fo highest enegy need adial coection of magnetic field Isochonous Sepaated secto cycloton at PSI

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17 Synchoton constant o slowly aying magnetic field + RF field cicula tajectoy with constant adius Rconst High fequency esonato E(t) B Focusing magnet Bending magnet

18 Inceasing Field Inceasing Beam Enegy Synchoton Phase stability Paticles with p > p aie late deceleation E*L Paticles with nominal momentum p see no acceleating field E*L t Paticles with p < p aie ealy, they pick up momentum, E*L t

19 Altenating Gadient Focusing -D-F-D... Combined Function Lattice ODO Lattice sepaated function F dipole D dipole F... Peiodically oscillating beam-enelopes hoizontal etical

20 Stoage Rings Synchoton with constant magnetic field Need good field quality (Homogeneity of magnetic fields)) Stoage Ring Regula acceleation unit can be inteupted by insetions

21 Low Beta Insetion Beam enelope hoizontal etical Low beta Quadupole Lens Doublet

22 Lepton Stoage Ring Maximum Enegy Limited by emission of Synchoton Radiation Need lage RF powe fo high enegy Oscillation of the lepton beams ae damped P ~ E 4 /? ph? γ eu hf sin(φ) p tans. Had limit fo maximum achieable enegy HERA 7.5GeV P5.16MW 35.GeV P13.4MW Powe Loss Used as e+e- Collides B-Factoies Synchoton Light Souces Stetche Rings

23 e + -e - - Collide The highest enegy e + -e - - cicula acceleato waslep (Lage Electon Positon Collide) at Cen with 1GeV beam enegy und 7km cicumfeence. LEP is the last of a seies of lepton collides and maks the end of a lage deelopement (VEPP1, ADDA, SPEAR, DORIS, PETRA, PEP, TRISTAN). The physics of e+-e - collisions can be continued with a Linea Collide, but meanwhile: ENERGY FRONTIER LUMINOSITY FRONTIER FACTORIES Double stoage ings with ey lage beam cuents PEPII & KEK-B (1.5GeV c.m.) DAΦNE (1GeV c.m.)

24 Hadon Acceleatos lage est mass: synchoton adiation negligible Maximum Enegy achieed by lage magnetic fields and lage cicumfeence Supeconducting magnets needed to achiee lagest enegy Fast cycling acceleatos usually nomal conducting Beschleunige nomalleitend Need elatiely low RF powe No adiation damoing: lage sensitiity against distotions and eos Lage demands on field quality, noise suppession, feedback systems

25 Supeconducting Magnets Supeconducting wie: Twisted NbTi 6µm? filaments in a coppe matix LHC Ruhefodtype cable Supeconducting Acceleato Magnets

26 Electon-Hadon Collide HERA Only facility of its kind Double Stoageing with 6.3km Cicumfeence 9GeV Potons - 7.5GeV Leptons

27 Synchoton Light Stoage ings as bight light souces fo eseach in physics, chemisty, biology, mateial science and medicin Use of synchoton adiation what is synchoton adiation? Coutesy M. Shinake KEK/Sping8 RadiationD.exe

28 Lepton Beam Emittance Stochastic emission of synchoton adiation photons (Quantum effect) Stochastisc Excitation of the beam oscillations amplitudes Dispesion tajectoy D p/p Tajectoy fo offenegy paticle D hω x Design Tajecto (Obit) Dipolmagnet γ Stoage ings with small Dispesion D in bends small emittance e ~ D /b

29 Synchoton Light Souces high billiance lepton stoage ings To obtain small beam size, the obit deiation fo off-momentun paticles must be small Achomate stuctue zb DOPPEL BEND ACHROMAT ESRF Footpint Dipole 18 o Betaton Phase adance

30 Acceleatos at DESY HERA PETRA TTF DORIS LINAC II/ III DESY II / III

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33 DESY Tunnel with DESY II and III

34 DORIS nd Geneation Light Souce

35 PETRA II Acceleato fo Leptons and Potons

36 TTF a supeconducting Test linac diing a fee electon lase

37 Fine

38 BETATRON A A A A eb d eb d d da B d e dt ee dp da B dt d d E 4 4 π π π π φ φ φ A A H H B e d eb d e d p B p eb d ρ B A B H db/dt di φ /dt, E φ Azimuthal Acceleation d Guide Field coil

39 ideoe s Sketch of the Hambug Betaton