Angular distribution measurement of atoms evaporated from a resistive oven applied to ion beam production. (1st April 2021)

• Record Type: Journal Article
• Authors: Leduc, A.; Thuillier, T.; Maunoury, L.; Bajeat, O.
• Is Part Of: Journal of instrumentation. Volume 16:Number 4(2021)
• Publication Date: 2021-04-01
• Subjects: Accelerator Subsystems and Technologies -- Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)); Scientific apparatus and instruments -- Periodicals; 502.84
• DOI: 10.1088/1748-0221/16/04/P04001
• Languages: English
• ISSNs: 1748-0221

Abstract

Abstract: A low temperature oven has been developed to produce calcium beam with Electron Cyclotron Resonance Ion Source (ECRIS). The atom flux from the oven has been studied experimentally as a function of the temperature and the angle of emission by means of a quartz microbalance. The absolute flux measurement permitted to derive Antoine's coefficient for the calcium sample used: A=8.98± 0.07 and B=7787± 110 in standard unit. The angular FWHM of the atom flux distribution is found to be 53.7±7.3 ∘ at 848 K, temperature at which the gas behaviour is non collisional. The atom flux hysteresis observed experimentally in several laboratories is explained as follows: at first calcium heating, the evaporation comes from the sample only, resulting in a small evaporation rate. Once a full calcium layer has formed on the crucible refractory wall, the calcium evaporation surface includes the crucible's enhancing dramatically the evaporation rate for a given temperature. A Monte-Carlo code, developed to reproduce and investigate the oven behaviour as a function of temperature is presented. A discussion on the gas regime in the oven is proposed as a function of its temperature. A fair agreement between experiment and simulation is found.