1. Electron Beam Source Temescal SFIH – 270 – 2 Fernando Lloret Vieira
March 2014
Fernando Lloret Vieira

2. Electron beam source Index Electron beam gun Temescal SFIH – 270 – 2
Heat diffusion
Emitter
Coils and magnetic fields
In the MBE system

3. Electron beam gun
A cathode is placed a high potential and electron are leaked in a stream to the anode.
Cathode: It is operate at high negative potential.
Tungsten filament: It is heated to a bright glow for thermionic emission.
Anode: At ground potential, the anode accelerates the electrons in a vacuum environment as an electrostatic field.
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

4. Electron beam gun E-beam gun Emitter Heat diffusion SFIH - 270 - 2
Coil magnetic field
System

5. Temescal SFIH – 270 – 2
Filament is inside of a cavity and both (filament and cavity) are at the same negative potential. This cavity generates the electrostatic field which forms the beam.
Electrons are directed to the ground potential of the material in the crucible.
The electromagnetic coils direct the beam, and the surrounding magnetic fields guide and focus the beam on the target.
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

6. Temescal SFIH – 270 – 2
The design of the Temescal e-beam use a 270º geometry
The crucible must be water cooled V
Powers as high as 300kW
Geometry of the emitter can reduce contamination of the electron source and electron beam scanning range can be expanded
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

7. Cold-hearth containment
Heat diffusion
The energy of the beam is so intensely concentrated on the surface of the evaporant that it forms a pool of molten evaporant.
In the evaporation from a water-cooled crucible, high boiling point materials remain in a solid “skull” at the interface with the crucible.
Cold-hearth containment
The heat diffusion mechanism is a combination of conduction and convection.
The magnitude of heat flow is proportional to the first power of temperature
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

8. Emitter
Formed by an anode, a cathode and a filament inside a cavity, the emitter generates the beam by thermionic emission.
Emission voltage: 4 to 10kV
Filament voltage: 12V maximum
Filament current: 50A maximum
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

9. Emitter Filament clamps & screws Filament Anode E-beam gun Emitter
Heat diffusion
SFIH
Coil magnetic field
System

10. Coils and magnetic fields
Coil extensions
Magnet
Magnetic coils
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

11. Coils and magnetic fields
Basic view of the SFIH – 270.
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

12. Coils and magnetic fields
The field of the permanent magnet is used to maintain the beam on the hearth area
Magnet
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

13. Coils and magnetic fields
Magnetic coils
The deflection coil is used to accomplish X-Y beam sweep
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

14. Coils and magnetic fields
Magnetic coils
Magnetic suppressor
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

15. Coils and magnetic fields
Magnetic coils
Magnetic suppressor
Pole extension
The pole extension pieces serve to defocus the beam and enlarge the size of the spot.
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

16. Coils and magnetic fields
Magnetic coils
Magnetic suppressor
Pole extension
Coil shield
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

17. Coils and magnetic fields
Magnetic coils
Magnetic suppressor
Pole extension
Coil shield
Pole piece
The lateral pole pieces supply the field to bend the beam toward the crucible.
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

18. Coils and magnetic fields
Pole piece
Coil shield
Crucible
Pole extension
Emitter
Electro magnetic coil assembly
E-beam gun
Emitter
Heat diffusion
SFIH
Coil magnetic field
System

19. In the MBE system E-beam gun Emitter Heat diffusion SFIH - 270 - 2
Coil magnetic field
System

20. In the MBE system Carbon e-gun Silicon e-gun E-beam gun Emitter
Heat diffusion
SFIH
Coil magnetic field
System