doi:10.1088/1748-0221/17/07/P07032engIguaz, F. J.Dafni, T.Canellas, C.Castel, J. F.Cebrián, S.Garza, J. G.García Irastorza, I.Luzón, G.Mirallas, H.Ruiz-Chóliz, E.Microbulk Micromegas in non-flammable mixtures of argon and neon at high pressureART-2022-130321We report on a systematic characterization of microbulk Micromegas readouts in high-pressure Ar+1%iC4H10 and Ne+2%iC4H10 mixtures. Experimental data on gain, electron transmission and energy resolution are presented for a wide range of drift and amplification voltages and pressures from 1 bar to 10 bar for the argon mixture and from 5 bar to 10 bar in the neon mixture, in steps of 1 bar. Maximum gains higher than 1.7 × 103 (1.7 × 104) in the argon (neon) mixture are measured for all pressures, without the significant decrease with pressure typically observed in other amplification structures. A competitive energy resolution at 22.1 keV, but with a slight degradation with pressure, is observed: from 10.8% at 1 bar to 15.6% FWHM at 10 bar in Ar+1%iC4H10 and from 8.3% at 5 bar to 15.0% FWHM at 10 bar in Ne+2%iC4H10. The experimental setup, procedure and the results will be presented and discussed in detail. The work is motivated by the TREX-DM experiment, that is operating in the Laboratorio Subterráneo de Canfranc with the mentioned mixtures, although the results may be of interest for other applications of time projection chambers at high pressures.2022http://zaguan.unizar.es/record/12674210.1088/1748-0221/17/07/P07032http://zaguan.unizar.es/record/126742oai:zaguan.unizar.es:126742info:eu-repo/grantAgreement/ES/AEI/PID2019-108122GB-C32info:eu-repo/grantAgreement/EC/FP7/240054/EU/Novel Developments in Time Projection Chambers (TPCs) for Rare Event Searches in Underground Astroparticle EXperiments/TREXinfo:eu-repo/grantAgreement/EC/H2020/788781/EU/Towards the detection of the axion with the International Axion Observatory/IAXOplusThis project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 788781-IAXOplusinfo:eu-repo/grantAgreement/ES/MINECO/FPA2016-76978-C3-1-Pinfo:eu-repo/grantAgreement/ES/MINECO/PID2019-108122GB-C31info:eu-repo/grantAgreement/ES/MINECO/PID2019-108122GB-C33Journal of Instrumentation 17, 7 (2022), P07032 [11 pp.]All rights reservedhttp://www.europeana.eu/rights/rr-f/info:eu-repo/semantics/openAccess