1. KEK (High Energy Accelerator Organization), Japan
CAT-KEK SOKENDAI School on Spallation Neutron Source: Accelerator Physics ＆Technological Aspects
February 2 – 8, 2004, Centre for Advanced Technology, Indore, India
ION SOURCES
Akira Takagi
KEK (High Energy Accelerator Organization), Japan

2. ION SOURCES(1) Early History of the Particle Accelerator
Production Methods of Negative Ion
Types of Negative Hydrogen Ion Source
KEK-PS H- Ion Source
LaB6 Filament
Beam Chopping
Secondary Electron by Ion Impact
Heavy/Metal Negative Ion

3. Early History
The First artificially induced nuclear transmutation. (Rutherford,1919)
16N + 4He  17O + 1H
a-particles (7 MeV, 2x107 m/s) from radium
The results as a whole suggest that if a-particles –or similuar　projectiles- of still greater energy were available for experiment, we might expect to break down the nuclear structure of many of the lighter atoms.
Rutherford, Phil. Mag. 37, 578 (1919)

4. Cockcroft-Walton’s Voltage Multiplier
The first nuclear disintegration by nuclear projectiles artificially produced in a man-made accelerator.(1932)
7Li + 1H  4He + 4He (+17.3MeV)
Cockcroft, Walton, Proc. Roy. Soc. A137, 229(1932)

5. Charge Transfer Processes (H+ -> H-)

6. Charge Exchange (D-)

7. Electron Affinities for atoms and molecules

8. H- Ions from Duoplasmatron

9. H- from Duoplasmatron

10. Potential distribution at the metal surface

11. PIG (Penning Ion Gauge) Type

12. Magnetron H- Production (Surface Production)

13. Magnetron Type

14. Multicusp Surface H- Ion Source

15. Multicusp Volume Production H- Ion Source

16. Multi-Cusp Negative Hydrogen Ion Source (Surface Production Type) BLAKE-I

17. KEK-PS Ion Source just before Installation

19. Electron Suppression

20. LaB6 & Tungsten LaB6 : W=2.67 eV 9 A/cm2 :1900 K W : W=4.55 eV

21. LaB6 Filament (15 mm dia.)

22. Surfase Analysis of LaB6 Filament
After 1000 hrs operation

23. LaB6 Filament ＆ Cathode Flange

24. After 3000 hrs Operation

25. LaB6 Filament (20 mm dia.)

26. LaB6 Filament＆Cathode Flange (Volume Source)

27. Empty Cs Ampoules & Cs-Glass Reactants

28. 750 keV Pre-Injector for 12 GeV PS

29. Ratio of Negative Hydrogen Ions

30. Operating Parameters Multicusp Surface production Negative Hydrogen Ion Source BLAKE-I
ARC Current A
ARC Voltage V
ARC Pulse Width msec
Converter Voltage V
Gas Flow Rate cc/min
Filament Current & Voltage
FIL-1 72A x 8.0 V(1400 C)
FIL-2 73A x 8.1V (1390 C)
Cockroft-Walton Generator Voltage kV
Beam Current mA

31. Beam Pulse : Ion Source Extraction & Linac Entrance
U : Voltage drop of the terminal voltage M : Ion source output (H-) L : Linac Input (H-)

32. Production of Direct-Chopped H- Ion Beam

33. Fast chopped H- beam (2 MHz) by the direct modulation of converter voltage

34. Radio Frequency Discharge

35. Radio Frequency Skin Depth (Xe)

36. Secondary Electron Emission
In the case of electron impact :
The energy of the primary electron must be higher than the energy determined by the work function of the metal surface.
In the case of positive ion impact,:
The secondary electron can be induced only if the sum of the potential energy E and the kinetic energy Ei is higher than twice the value of the work function f.
E + Ei > 2f

37. Secondary Electron Emission by Ion Impact

38. Faraday Cup Signals by H-/+/o Beam (Without Secondary Suppression)

39. Secondary electron Coefficients by H-/+/o Beam

41. No Conclusion Tomorrow’s my lecture:
Volume Production Negative Hydrogen Source
Early results in KEK
Recent results for J-PARC
H- diagnostics (with laser)