Particle Sources. Dan Faircloth Ion Source Section Leader Rutherford Appleton Laboratory. -The most important part of the whole machine

Transcription

1 Particle Sources Dan Faircloth Ion Source Section Leader Rutherford Appleton Laboratory -The most important part of the whole machine

2 Light ions e.g. С 4+ Protons Positrons e + Positively Charged Particles Highly charged ions e.g. Ag 32+ μ + Electrons e Muons μ Negative ions Antiprotons H Negatively Charged Particles Photons Neutrinos ν e ν μ ν τ Neutral particles Neutrons H 0 Neutral Particles n Fully stripped nuclei e.g. U 92+ Exotic nuclei e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons

3 Microwave discharge Light ions e.g. С 4+ Electron Cyclotron Resonance Electron beam Vacuum arc Plasmatrons Exotic nuclei Protons Laser plasma Highly charged ions Fully stripped nuclei e.g. U 92+ Positrons e + e.g. Ag 32+ e.g. Lr 103+ μ + p Electrons e Thermo Plasma + other Photo Muons μ Negative ions Penning and Magnetron Multicusp e H Particles and Sources Polarised particles Antiprotons H Surface plasma Surface converter Filament and RF Volume Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons

4 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons

5 Electrons The Electron! Corpuscles George Johnstone Stoney 1894 J. J. Thomson 1897

6 Early 1870 s Hermann Sprengel William Crookes Improved mercury pump 10-5 mbar

7 Electron Guns Inferiority complex Because they re so small! Ion Sources?

8 Particle sources/guns consist of: Something to make the particles + An extraction system to create and accelerate a beam

9 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Thermionic Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons

10 Fredrick Guthrie British scientific writer and professor - + A negatively charged red hot metal ball looses charge......whereas a positively charged one keeps its charge Elements of Heat in 1868 First experimental observation of thermionic emission

11 Thermionic Emission Ammeter Swap polarity Thomas Edison The Edison effect

12 Thermionic Emission Ammeter Thomas Edison The Edison effect

13 Thermionic Emission Corpuscles J A G T 2 e W kt Richardson s Law J. J. Thomson 1897 Cambridge University 1901 Owen Richardson Same form as the Arrhenius equation Current increases exponentially with temperature

14 Number of Electrons Thermionic Emission Work Function W = a few ev Fermi-Dirac 0 K Free electrons E f Fermi Level E 0 Energy Vacuum Level J A G T 2 e W kt For a good electron emitter you need: Lowest possible work function Highest possible temperature

15 Work Function (ev) Cathode Materials 5 4 Mo 4.2 ev W Ta 4.5 ev 4.1 ev Cs 1.9 ev BaO W 1 ev Commonly used CeB 6 LaB 6 W 2.5 ev High brightness Ideal material (does not exist!) Practical Operating Temperature (Kelvin)

16 Electron beam Child-Langmuir Law C.D Child 1911 V Cathode Cathode E Emission (Space charge limited extraction) Anode Ground Irving Langmuir 1913 Electron emitting material Q d j d 2e m 2 e V 3 2

17 Perveance Limit I Beam I V Extraction Perveance P V Extraction

18 Electron beam Cathode Anode Pierce Extraction Geometry V Cathode Ground

19 Electron beam Cathode Anode Pierce Extraction Geometry V Cathode 67.5 E x = E y = 0 Ground E x = E y = 0

20 Electron beam Cathode Anode Gridded Extraction (A triode amplifier) V Cathode Ground Heater V grid

21 YU 171 Thermionic dispenser cathode with integrated heater and grid Sinter of W and BaO 1cm 2 12 W heater Swiss Light Source 90 kv triode gun with Pierce geometry 1000 ns, 3 nc long pulses or 1 ns, 1.5 nc short pulses Lifetime = several thousand hours

22 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Photo Particles and Sources Thermionic Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

23 Photo Emission First observed by Heinrich Hertz in 1887 UV Theoretical explanation by Einstein in 1905

24 Number of Electrons Photo electric emission Work Function W Free electrons Photons E f E 0 Energy Fermi Level Vacuum Level Quantum efficiency (QE) = Number of electrons produced Number of incident photons

25 Electron beam Photo Emission Gun Cathode Anode V Cathode Ground Photo cathode Materials: Cu QE 0.001% GaA QE 5% Cs 2 Te QE 10% Laser beam

26 Cornell DC Photoemission gun 20mA average current at 250kV

27 Space Charge

28 Space Charge Space charge force scales as 1/γ 2 At 500 kev electron γ= 2 (940 MeV proton γ = 2)

29 Another reason to use lasers is Lasers are so fast they can easily beat Child-Langmuir (to be fair, so can gridded extraction) Cathode Anode Photo Cathode Cs 2 Te Very short Beam pulse Emitted current is not limited by space charge Pancake beam Ground Very short laser pulse

30 RF Photemission Source Resonant RF cavity (normal or super conducting) High Fields > 10 MVm GHz RF feed E Emission Laser pulse RF waveform Laser pulse Time Photo Cathode Cs 2 Te E Emission Pancake beam pulses Very short laser pulses RF feed 1.3 GHz

31 Normally conducting Super conducting 20 ps, 1 nc pulses (50 A pulse) 15 ps, 1 nc pulses (67 A pulse) High brightness low emittance guns for FEL

32 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Thermo Plasma + other Photo Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

33 Plasma Cathode Very high electron currents can be extracted from plasma cathode electron sources Plasma chamber Cathode Long cathode lifetimes Anode Ground Other electron sources: Combinations of those already mentioned e.g. photo-thermionic > 1kA! Rarely used in accelerators: Field emission from needle arrays Diamond amplifiers Etc...

34 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Plasma Sources Fully stripped nuclei e.g. U 92+ Exotic nuclei e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

35 Ion Sources

36 Ionisation Neutral Atom Most sources rely on electron impact ionisation

37 Ionisation Neutral Atom Most sources rely on electron impact ionisation

38 Ionisation e- e- Positive Ion Most sources rely on electron impact ionisation

39 Approximate Current Range Electrical Discharges Log I 100 A Thermal Arc Discharge Arc Discharge A Glow Discharge µa na Dark Discharge Background Ionisation 70 V Townsend Breakdown Breakdown Voltage Voltage Between Anode and Cathode

40 Approximate Current Range 1G A 1M A 100 A Quark Gluon Plasma Fusion Z-Pinch Thermal Arc Discharge Arc Discharge A Glow Discharge µa na Dark Discharge Background Ionisation 70 V Townsend Breakdown Breakdown Voltage Voltage Between Anode and Cathode

41 Basic Plasma Properties Density, n (per cm 3 ) n e = density of electrons n i = density of ions n n = density of neutrals Charge State, q H + q = +1 Pb 3+ q = +3 H q = K = 1 ev Temperature, T (ev) T e = temperature of electrons T i = temperature of ions T n = temperature of neutrals

42 Temperature Distribution If thermalised velocity distributions should follow Maxwell Boltzmann statistics However, in magnetic fields: v x v y v z

43 Magnetic Confinement Particles spiral along magnetic field lines

44 Solenoid field

45 Dipole field B

46 Hexapole S N N S S N

47 Multicusp Confinement

48 Collisions e- Concept of mean free path does not work in a plasma The average time it takes for a particle to be deflected by 90 Charged particle trajectories are constantly affected by their neighbours electric fields > 90 e- Relaxation time = 90 deflection time

49 Percentage Ionisation n i n i + n n > 10 % Highly ionised < 1 % Weakly ionised

50 Quasi Neutrality Σ q i n i = n e

51 Debye Length e- e-

52 Plasma Sheath Electrons have a greater mobility

53 Plasma Pioneers Heinrich Geißler Gas discharge tube and mercury displacement pump just less than 1 mbar Julius Plücker Mid 1850 s University of Bonn magnetism could move the glow discharge

54 Drawing of Geissler tubes from 1860 s French physics book

55 Canal Ray Source In 1886 Eugen Goldstein discovered canal rays Glass Tube Perforated Cathode Anode Vacuum Pump Positive Ion Beams Discharge Power Supply V

56 Arthur Dempster Electron Bombardment Source (1916) Anode Extraction Electrode Gas Feed Filament Power Supply 2-10 A Cathode Filament Beam Early mass spectrometry - + Discharge Power Supply A + - Extraction Voltage Supply 1-10 kv

57 Plasmatrons Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

58 Plasmatron (late 1940s) Conical Intermediate Electrode Anode Manfred von Ardenne Filament Power Supply A Gas Feed Cathode Filament Extraction Electrode Beam - + Discharge Power Supply A + - Extraction Voltage Supply 5-50 kv

59 Duoplasmatron (1956) Solenoid Solenoid Field Iron Return Yoke Conical Iron Funnel Intermediate Electrode Anode Expansion Cup Manfred von Ardenne Filament Power Supply A Gas Feed Cathode Filament Extraction Electrode Beam - + Discharge Power Supply A + - Extraction Voltage Supply 5-50 kv Defocusing Solenoid

60 300 ma protons 150 μs pulses at 1 Hz CERN Duoplasmatron

61 Dan Faircloth CAS 2012 Particle sources/guns consist of: Something to make the particles + An extraction system to create and accelerate a beam The emission surface is critical to the quality of the beam

62 Plasma Plasma Plasma Meniscus Beam Meniscus Beam Meniscus Beam Plasma Mencius Plasma Electrode Extraction Electrode Plasma Electrode Extraction Electrode Plasma Electrode Extraction Electrode Convex Flat Not including space charge effects Concave

63 Plasma Meniscus Beam Space Charge Plasma Electrode Extraction Electrode Neutralising Particles Optimum = slightly concave 0% 95% Percentage compensation

64 Suppressor Electrode Plasma Electrode Suppression Electrode Ground Electrode Plasma Compensating particles reflected by the Suppression Electrode Extracted Beam V (kv) Z (mm)

65 Emittance of Real Beams Halo Effect - Plasma boundary - Fringe fields How big is this beam? 95% emittance rms emittance

66 Brightness Be careful- Some definitions include factors of 2, 8 and π Are the emittances normalised?

67 Microwave Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

68 Microwave Ion Sources Off resonance = Microwave discharge ion sources On resonance = Electron Cyclotron Resonance (ECR) sources

69 Microwave discharge Plasmatrons Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

70 Microwave Discharge Ion Source Plasma Chamber Solenoids High Voltage Insulators Gas Feed RF in Beam Discharge Region Stepped RF Matching Section 100 mm Plasma Electrode Ground Electrode Suppressor Electrode 2.45 GHz commonly used

71 SILHI Microwave Source Rafael Gobin CEA Saclay Late 1990s 140 ma DC protons For one year!

72 Sophisticated Extraction System

73 Microwave discharge Plasmatrons Light ions e.g. С 4+ Protons Positrons e + Vacuum arc Highly charged ions e.g. Ag 32+ μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Fully stripped nuclei e.g. U 92+ Exotic nuclei e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

74 Vacuum Arc Ion Sources 1980s - Ian Brown and others Trigger Electrode Anode Expansion Region Extraction Aperture High Voltage Insulators Beam Cathode Solenoid Grids 50 mm Suppressor Electrode Ground Electrode

75 Lawrence Berkley Lab MEVVA GSI MEVVA 15 ma of U 4+ ions

76 Microwave discharge Plasmatrons Light ions e.g. С 4+ Protons Positrons e + Vacuum arc Laser plasma Highly charged ions e.g. Ag 32+ μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Fully stripped nuclei e.g. U 92+ Exotic nuclei e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

77 Laser Plasma Ion Sources Target Plasma Plume Target Chamber Expansion Region Extraction Aperture High Voltage Insulators Suppressor Electrode Beam Target Rotation Mechanism Laser Beam Focusing Optics Salt Window 200 mm Ground Electrode High Power Laser Joules per pulse!

78 Final Optics Target Vessel ITEP Laser source at CERN

79 ITEP Laser source at CERN

80 TWAC at ITEP Moscow 7 mа, 10 μs pulses of С 4+ Very Recently Masahiro Okamura, BNL and RIKEN demonstrated Direct Plasma Injection into an RFQ

81 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Electron Cyclotron Resonance Exotic nuclei Highly charged ions e.g. Ag 32+ Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

82 ECR Ion Source Plasma Chamber A Super Conducting Solenoids High Voltage Insulators B Gas Feed RF in Beam ECR Surface Stepped RF Matching Section 100 mm A Plasma Electrode Ground Electrode Suppressor Electrode Hexapole Magnetic Field B Section on B-B Section on A-A

83 ECR Surface RF in Beam ECR Surface

84 28 GHz superconducting VENUS ECR Daniela Leitner LBNL Late 2000s 200 eμa U 34+ ions 4.9 eμa U 47+ ions

85 VENUS ECR

86 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Electron beam Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

87 Electron Beam Ion Sources Electron Gun Electron Beam Drift Tubes Superconducting Solenoid Magnetic Shielding Electron Dump Extraction Electrode 100 mm Ionisation Chamber Drift TubeV Trapping and Ionisation Phase Z Stepwise ionisation

88 Electron Beam Ion Sources Electron Gun Electron Beam Drift Tubes Superconducting Solenoid Magnetic Shielding Electron Dump Extraction Electrode Drift TubeV 100 mm Ionisation Chamber Extraction Phase High Charge State Positive Ion Beam Z

89 Jim Alessi BNL 1.7 ema, 10 µs, 5 Hz Ag 32+ ions Fully stripped nuclei can be obtained in EBIT mode

90 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

91 Negative Ion Sources Ripping electrons off is easy! - It is much harder to add them on. Not all elements will even make negative ions Hydrogen has an electron affinity of ev H has a much larger cross section than H 0 30 times for e - collisions 100 times for H + collisions H are very fragile!

92 Applications Tandem accelerators Cyclotron extraction Multi-turn injection into rings Stripping foil Neutral Beams Protons H - from Linac

93 Early attempts at producing negative ion beams: 1. Charge exchange of positive beams in gas cells - very inefficient 2. Extraction from existing ion sources

94 Off Axis Duoplasmatron Extraction Displacement 1960 s George Lawrence Los Alamos

95 Off Axis Duoplasmatron Extraction Electron Current (ma) Electron Current H Current H Current (μa) Displacement (mm)

96 Negative Ion Beam Negative Ion Extraction Electrons B Electrons will also be extracted Up to 1000 times the H current! Use a magnetic field Dump must be properly designed Electron Dump Best sources: only 0.5 times H current

97 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Surface plasma Highly charged ions e.g. Ag 32+ Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

98 Early 1970s Budker Institute of Nuclear Physics Novosibirsk Production of H ions by surface ionisation with the addition of ceasium Surface Plasma Sources (SPS) Gennady Dimov Yuri Belchenko Vadim Dudnikov

99 5 g Caesium Ampoule

100

101 Work Function (ev) Pure molybdenum 4.6 Caesium Coverage Pure Caesium 0.6 Cs Thickness (monolayers) 1

102 Fermilevels Cs Cs Cs P H H

103 Pressure (mbar) Pressure (mbar) Control caesium oven temperature to vary caesium vapour pressure to control caesium coverage E E E-03 Log Scale Cs Oven Temperature (Degrees C) 1.0E Cs Oven Temperature (Degrees C)

104 Light ions e.g. С 4+ Protons Positrons e + Highly charged ions e.g. Ag 32+ μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Penning and Tauons Surface plasma Magnetron Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Fully stripped nuclei e.g. U 92+ Exotic nuclei e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

105 Magnetron Source Anode Hydrogen Cathode Anode Hydrogen B Cathode Caesium Vapour Extraction Electrode B H Beam Electrons 10 mm Extraction Electrode Beam Magnetic Pole Pieces

106 80 ma of H but only at low duty cycles < 0.5% Fermilab Magnetron

107 Penning SPS Ion Sources Invented by Dudnikov in the 1970 s Very high current density > 1 Acm -2 Low noise Does not work without ceasium

108 Penning Pole Pieces Aperture Plate Negative Ion Beam Extraction Electrode Discharge Region Hollow Anode Source Body Cathode Mica Air Cooling Channels Ceramic Spacer Copper Spacer Mounting Flange 10mm Water Cooling Channels

109

110 +17 kv Extraction Voltage 50 A Discharge Negative Ion Beam Caesium Vapour Heated Transport Line Caesium Oven Source Runs at 50 Hz Rep Rate Hollow Anode Piezo Hydrogen Valve 10mm H 2

111 Cathode Hydrogen Feed Hollow Anode Air Cooling Heated Caesium Transport Line Source Body Discharge Power Feed Thermocouples

112 Aperture Plate

113 Extraction Mount Extraction Electrode Support Insulators ISIS Ion Source 60 ma 2 ms 50 Hz H beams Caesium Shields

114 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Surface plasma Highly charged ions e.g. Ag 32+ Multicusp Surface converter Filament Exotic nuclei Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

115 Filament Cathode Multicusp Surface Converter Source Surface Converter Electrode -300 V Heated Filament Cathode Hydrogen Feed Anode Outlet Aperture H Beam Anode Multicusp Magnets Caesium Vapour 100 mm Multicusp Magnets

116

117 LANL with multiple filaments: 1 A of H

118 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Exotic nuclei Highly charged ions e.g. Ag 32+ Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p e H Polarised particles Volume Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

119 Volume Production Marthe Bacal Ecole Polytechnique mid 1970 s H 2 * + e ( 1 ev) H + H 0 Dissociative attachment of low energy electrons to rovibrationally excited H 2 molecules Developed by Ehlers + Leung at LBNL

120 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Exotic nuclei Highly charged ions e.g. Ag 32+ Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p Multicusp e Filament H Polarised particles Volume Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

121 Multicusp Filament Volume Source Multicusp magnets Hydrogen feed High electron temperature plasma region A Low electron temperature plasma region Extraction electrode H Beam B Multicusp magnets Cathode Filament B Plasma chamber 100 mm Anode Filter magnets A Electron dump Plasma chamber B Section on B-B Section on A-A Many Variations: e.g. JPARC use a LaB 6 cathode

122 D-Pace 15 ma DC H Multicusp Volume Source

123 Light ions e.g. С 4+ Protons Positrons e + μ + Electrons e Muons μ Negative ions Particles and Sources Antiprotons H Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Exotic nuclei Highly charged ions e.g. Ag 32+ Fully stripped nuclei e.g. U 92+ e.g. Lr 103+ p Multicusp e H RF Polarised particles Volume Higgs Bosons Zoo of curiosities Tauons Mesons Baryons W + Z Bosons Dan Faircloth CAS 2012

124 RF Power Supply 50 kw Internal RF Solenoid Antenna High electron temperature plasma region Volume Source A Low electron temperature plasma region B Extraction electrode H beam B Multicusp magnets Plasma chamber 100 mm Anode Filter magnets A Electron dump Plasma chamber B Section on B-B Section on A-A

125 38 ma H 1 ms, 60 Hz SNS ion source

126 External RF Antenna Multicusp Source Pulsed hydrogen Ignition element Multicusp magnets A External antenna solenoid Filter magnets Extraction electrode H Beam External Antenna solenoid B Multicusp magnets Ignition anode B Ceramic plasma chamber Funnel and aperture electrode Electron dump Ceramic plasma chamber 100 mm A Section on B-B B Section on A-A

127 DESY Source Jens Peters Late 1990 s 40 ma H 150 μs, 3 Hz

128 Microwave discharge Light ions e.g. С 4+ Electron Cyclotron Resonance Electron beam Vacuum arc Plasmatrons Exotic nuclei Protons Laser plasma Highly charged ions Fully stripped nuclei e.g. U 92+ Positrons e + e.g. Ag 32+ e.g. Lr 103+ μ + p Electrons e Thermo Plasma + other Photo Muons μ Negative ions Penning and Magnetron Multicusp e H Particles and Sources Polarised particles Antiprotons H Surface plasma Surface converter Filament and RF Volume Photons Neutrinos Neutral particles ν e ν μ ν τ Neutrons H 0 n Higgs Bosons Zoo of curiosities Tauons Mesons Baryons Accelerator Facilities W + Z Bosons

129 Which Source? Type of particle Current, duty cycle, emittance Lifetime Expertise available Money available Space available

130 Reliability is King! Operational sources should deliver >98% availability Lifetime compatible with operating schedule Ideally quick and easy to change Short start-up/set-up time

131 cryogenic systems timing systems machine interlocks communication systems Reliability also depends on: low voltage power supplies Everything Else! cooling water human error hydrogen vacuum systems temperature controllers personnel interlocks mains power high voltage power supplies material purity control systems compressed air supplies laser systems

132 Developing Sources Driven by demand for Increases in current, duty cycle and lifetime Improvements in beam quality Development strategy Simulations Test stands Diagnostics

133 The Development Cycle Hardware Experiments Simulations

134 Summary Particle sources are a huge interesting subject A perfect mixture of engineering and physics We have only scratched the surface

135 Thank you for listening