Dipole Puller Chuck

Older Cyclone30 cyclotrons use a small single permanent dipole magnet chuck installed in the puller lens of the H¯ ion source to extract electrons from the negative hydrogen ion beam. This single dipole magnet system works well to extract the electrons from the beam, but unfortunately it also deflects the H¯ beam into the downstream ground lens. This causes large scale wear and erosion of the lens as shown in Fig. 1. This is a problem because it adversely affects the focusing capability of the ground lens, and is a costly maintenance repair. Newer Cyclone30 cyclotrons do not have this problem.

The Double Dipole Puller Chuck corrects this problem by using a double-dipole magnet such that electrons are removed as before, but the initial dipole field followed by a second dipole magnetic field of opposite sense ensures that the H¯ beam trajectory is instantly corrected, so that it remains centred on axis. This eliminates ground lens erosion, so that this lens continues to focus the beam properly, and replacement of the ground lens as a regular maintenance item is no longer required. Fig. 2 shows the physical Double Dipole Puller Chuck, and Fig. 3 shows the device installed in the puller lens of the ion source.

Fig. 2: The Doube Dipole Puller Chuck; Fig. 3: The Double Dipole Puller Chuck installed in the puller lens.

Features

• Provides electron filtering of ion source H¯ beam in older Cyclone 30 Cyclotrons.
• Replaces Single Dipole Puller Chuck
• Ensures H¯ beam exits the ion sources lenses centred on lens axis.
• Eliminates erosion and wear on ion source ground lens.
• Eliminates degradation of ground lens focusing due to erosion and wear.

Performance

• Removes electrons from 12 keV to 30 keV H¯ ion source beams.
• H¯ beam experiences ∫ Bdl = 0 in beam direction (refer to Puller Chuck #1 Plot).
• Peak magnetic flux density = -250 Gauss followed by 250 Gauss (refer to Plot).

Specifications

• Diameter: 48 mm
• Thickness: 12 mm
• Automatic Fit into Puller Lens in pre-year 2000 Cyclone30’s