ECRIS – Electron Cyclotron Resonance Ion Source

To obtain relevant ion beams for the cyclotron a small 10 GHz ECR ion source (Fig.1) has been built at HIL. ECR discharge takes place in the stainless steel chamber, 50 mm inner diameter, 250 mm long. This chamber is an extension of a coaxial line, feeding RF to the plasma, similarly to the Nanogan. The magnetic confinement of the plasma in radial direction is obtained by the hexapol surrounding the chamber. This hexapol consists of 12 segments made of NdFeB permanent magnets. Trough the 1 mm gap between the hexapol and the chamber tube a cooling oil is pumped. The axial magnetic field is created by 8 water cooled coils. Each two coils are supplied with a current from separate power supply. This configuration allows to obtain relevant magnetic profile, tuned for the maximum of the beam current. The combination of the criogenic and turbomolecular pump provides the vacuum of about 5×10^8 in the beam area.

Fig. 1. Schematic view of the ECR ion source. 1. coils 2. hexapol 3. plasma chamber 4. coaxial line 5. tuner 6. RF injection 7. exit hole 8. Einzel lens 9. yoke.

Main parameters of the ion source:

RF frequency: 9.6 GHz
extraction voltage: 10 kV
max. magnetic field on the axis: 6.5 kG
min. magnetic field on the axis: 2.4 kG
hexapole field on the chamber surface: 5.2 kG
RF power: up to 300 W

Tabela 1. Ion beams available from the Warsaw ECR ion source, currents in eµA
Ion/q	+1	+2	+3	+4	+5	+6	+7	+8	+9	+10	+11	+12	+13
₄He	220
₁₀B		10
₁₁B		47	57	21
₁₂C		100	120	55	6
₁₄N		160	180	130	75
₁₆O			190	180	85	32
₁₈O			45
₁₉F			65	80	47	22	10	2
₂₀Ne			150	145	115	90	49	5
₂₂Ne				120
₃₂S					109		118	56	16	6
₄₀Ar						90	65	58	15		5
₈₄Kr							30	32	27	20	14		4

Fig.2. Example of the charge state distribution: sulfur optimized for S+7.

Fig.3. Examples of the ECR ion source possible applications (in red).

The Warsaw ECR source has been built under general supervision of Dr Krzysztof Sudlitz (k.sudlitz@inetia.pl).