Thermal Simulation Studies for the Characterization of a Cyclotron Liquid Target with Thick Niobium Target Windows

Sergio J C Do Carmo,Francisco Alves,Pedro M De Oliveira

doi:10.3390/app112210922

Abstract

This work presents a simulation model developed with the aim to represent and study the thermal behavior of cyclotron liquid targets. Understanding and improving the thermal behavior of the target system is fundamental to improving the target overall performance, especially when using thick target windows, for which a larger amount of heat generated can be limiting. ANSYS CFX and SRIM software were used to develop a simulation model representing the IBA Nirta® Ga-68 liquid target system, to study the use of thick niobium target windows. The model was validated by comparing the results with experimental data obtained for the same liquid target system. In the present study, simulation results and temperature distributions of the main target components were obtained by studying the main parameters of interests, such as the initial temperature and mass flow rate of the coolants, and also distinct target windows with different thicknesses.

Highlights

Recent years have witnessed growing interest in radiopharmaceuticals labeled with several radiometals of clinical interest, such as 68Ga and 64Cu [1,2]
The thermodynamic behavior of the IBA Nirta® Ga-68 liquid target system was implemented on the ANSYS-CFX (v. 19.2, ANSYS, Inc., Canonsburg, PA, USA) software based on the governing equations and finite element method (FEM)
This work presents the development of a simulation model representing the thermal behavior of the IBA Nirta® Ga-68 liquid target, by coupling the energy deposited by the beam and the thermal physics involved in the irradiation of a cyclotron liquid target

Summary

Introduction

Recent years have witnessed growing interest in radiopharmaceuticals labeled with several radiometals of clinical interest, such as 68Ga and 64Cu [1,2]. The IBA Nirta® Ga-68 liquid target (IBA, LouvainLa-Neuve, Belgium), developed for the production of 68Ga from the proton irradiation of a 68Zn-based liquid target solution, uses thick niobium target windows instead of the conventional thin havar window used for the production of 18F. Niobium was used since its chemical inertness avoids the introduction of additional metallic impurities in the target solution [5]. The irradiation of such thicker target windows comes, at the expense of significantly higher heat generated in the window, due to an increased loss of beam energy, with the potential to lead to fast material degradation or even rupture [3]. It is crucial to study and understand the thermal performance of the liquid target system in order to improve its capacity to remove heat, which will allow for the increase in the beam current reaching the target, and will improve the overall target performance

Methods

Results

Conclusion