Monochromatic ion and electron beams by ionization of cold atoms

46 Pages·2012·4.72 MB·English

Monochromatic ion and electron
beams by ionization of cold atoms
DDaanniieell CCoommppaarraatt
Laboratoire Aimé Cotton, CNRS, UPR3321,
Bât. 505, Univ Paris-Sud, Orsay, 91405 FRANCE
Experiments in the « Cold atoms and molecules group »
Cesium Magneto-Optical Trap
(P. Pillet, H. Lignier, D. Comparat)
-Cold cesium molecules (formation, vibrational cooling, trapping, ..)
Cs,Ytterbium MOT:
(D. Comparat, P. Cheinet, P.Pillet)
Cold Rydberg atoms (dipole blockade, plasma ….)
Stark & Zeeman (mol.) decelerators
(P. Pillet, J. Robert)
CERN
: antigravity, antihydrogen, Ps spectroscopy: (L. Cabaret, D. Comparat)
Production of ion and electron sources from cold atoms
(P. Pillet, D. Comparat)
-
+
Outline
(cid:1)
Electron and ion sources
(cid:1)
Laser cooled sources
(cid:1)(cid:1)
IIoonn bbeeaamm pprroojjeecctt
(cid:1)
Electron beam project
(cid:1)
Outlook
Outline
(cid:1)
Electron and ion sources
(cid:1)
Laser cooled sources
(cid:1)(cid:1)
IIoonn bbeeaamm pprroojjeecctt
(cid:1)
Electron beam project
(cid:1)
Outlook
Ion (focused) source applications
Secondary particles:
M ,M+,M-,…
0
Sputtering
Array of holes FIB pattern Microlens
Imaging
Test surface with various
FIB image of a Al sample
sizes tin (Sn) balls
Deposition
IIoonn aanndd EElleeccttrroonn BBeeaamm iinndduucceedd ddeeppoossiittiioonn
Electron source applications
• Particle accelerator, Televisions, …
• Electron spectrometers:
• EELS
(Electron Energy Loss Spectroscopy)
• Imaging + Scanning microscope
• Electron irradiation:
• Mass spectrometry,
• Sterilization, Desorption
• Linking or breaking polymers
http://ehs.virginia.edu/ehs/ehs.rs/rs.images/sem.coutesy.iowa.state.jpg
Electron sources
Ion source
AA ssiinnggllee wwiiddee--sspprreeaadd tteecchhnnoollooggyy ((LLMMIISS)) SSeevveerraall wwiiddee--sspprreeaadd tteecchhnnoollooggiieess
LLiiqquuiidd MMeettaall IIoonn SSoouurrccee •Thermionic (LaB )
6
• Photocathode
• Cold emission
• Plasma
7nm
Limitations:
Limitations:
• few element possible
Ga, In, Cs, Bi, Au, Si, + Alloys… ∆
•Wide energy-spread E=0.3eV
• Gallium pollution
•Monochromators limits flux and brightness
∆
• Wide energy-spread E=5eV
•Complex Optics (chromatism) to focus
Important source parameters
Angle
m
Current (pA – A)
x’= v /v
x z
z
a
Position x
e
Emittance (normalized) : phase space
x,y
-2 -2 -1
BBrriigghhttnneessss ((AA mm ssrr eeVV ))
amount current in a spot,
invariant along the beam path no interactions, aberrations
D
Energy spread E: it limits the energy resolution and the
focusing properties
Important source parameters
Type LMIS Gas Field Plasma Trap (Penning)
∆
E=5eV Ion. Source
I (nA) 1000 0.01 10000 0.01
max
-2 -1 -1 5 6 9 3 5
B (A m sr .eV ) 10 -10 10 10 10
From: J. Vac. Sci. Technol. A 23 1498 (2005) + Handbook of Charged Particle Optics (2008)
(cid:1)(cid:1)
UU==1100 kkeeVV,, II==11 nnAA ssppoott ssiizzee ~~ 00..11 µµmm
Gun : Tungsten LaB Schottky CFEG
6
Brightness (A.m-2 sr-1 eV-1) 104 105 107 108
Cathode energy spread (eV) 1 0.5 0.4 0.3
(cid:1)(cid:1)
UU==11 eeVV,, II==1100 µµAA ssppoott ssiizzee ~~110000 µµmm
Outline
(cid:1)
Electron and ion sources
(cid:1)
Laser cooled sources
(cid:1)(cid:1)
IIoonn bbeeaamm pprroojjeecctt
(cid:1)
Electron beam project
(cid:1)
Outlook