Damage Characterisation of Tantalum Ion Source Electrodes and Reconditioning by Wire- and Powder-Based Laser Metal Deposition

International Journal of Refractory Metals and Hard Materials 2023
Tobia Romano, Dagnija Kroģere, Andris Ratkus, Hannes Lauer, Franz Marquardt, Maurizio Vedani, Diego Obrados, Markus Weinmann, Toms Torims

The internal ion source of the Advanced Molecular Image Technologies (AMIT) superconducting cyclotron uses cathodes made of pure tantalum to generate high energy H− ion beams for the production of isotopes for positron emission tomography. During service, the cathodes are impacted by high-energy ions from the plasma. The resulting erosion creates craters that reduce the current density of the extracted beam. The cathodes eventually need to be replaced when the ion source can no longer be activated. This research explores the possibility of repairing the tantalum cathodes used in the AMIT cyclotron through laser metal deposition additive manufacturing. The damaged parts were first characterised by 3D imaging, scanning electron microscopy, and Vickers microhardness to understand the damage mechanisms occurring during service and quantify the extent of the damage. Different repair strategies were then tested employing both high-purity tantalum wire and powder feedstocks and the properties of the reconditioned electrodes were determined. The ability of laser metal deposition to restore the damaged cathodes for use in the AMIT cyclotron has been demonstrated.

Keywords
Laser metal deposition | Tantalum | Additive manufacturing | Repair | PIG ion source | Abnormal grain growth
DOI
10.1016/j.ijrmhm.2023.106364
Hyperlink
https://www.sciencedirect.com/science/article/pii/S0263436823002640

Romano, T., Kroģere, D., Ratkus, A., Lauer, H., Marquardt, F., Vedani, M., Obrados, D., Weinmann, M., Torims, T. Damage Characterisation of Tantalum Ion Source Electrodes and Reconditioning by Wire- and Powder-Based Laser Metal Deposition. International Journal of Refractory Metals and Hard Materials, 2023, Vol. 116, Article number 106364. ISSN 0263-4368. e-ISSN 2213-3917. Available from: doi:10.1016/j.ijrmhm.2023.106364

Publication language
English (en)