Elliptical AE (EAE) and TAE mode instabilities have been observed in hydrogen-rich (nH/(nH+nD)~70-90% JET discharges of so-called “three-ion scenario”, i.e. D-(3He)-H three ion ICRH scenario , which is characterized by strong absorption of radio frequency waves at very low concentrations of the resonant 3He-ions. In the experiments, the core localized TAEs with a frequency fTAE ≈ 280 kHz were observed. Following the phase with TAE excitation, EAE modes at higher frequencies fEAE ≈ 550-580 kHz with mode numbers n=±1, ±3, ±5 were seen. These high frequency modes indicate that a MeV range population of trapped energetic ions was present in the plasma interacting with the modes via ω=nωDh+pωbh resonance (here ω, n are the frequency and toroidal mode number of AE, ωDh and ωbh are toroidal precession drift and bounce frequencies of the hot ions, and p is integer). The experimental evidence of the existence of the MeV-energy 3He-ions able to excite the AEs is provided by neutron and gamma-ray diagnostics as well as fast ion loss (FILD) measurements. It was found that the anomalous DD neutron rate in the ICRF-only heated plasma is provided by a population of energetic deuterons formed via elastic head-on scattering of the MeV 3He-ions on deuterium (knock-on effect): D(3He,3He)Dknock-on => D(Dknock-on,n)3He. Gamma-ray diagnostics  shows that some neutrons are also generated in the nuclear reaction 9Be(3He,n)11C, which takes place with 3He-ions in the MeV-range. The fast ion loss detector  indicates the MeV 3He-ion losses related to the core localized TAEs ended with a spike of monster sawtooth loss and then losses correlated to the EAE modes were observed. The analysis of FILD data indicates, the lost 3He-ion energies exceeding 2 MeV. The back-in-time orbit analysis of FILD data shows that the TAE-related 3He-ion losses are localised in the plasma centre (R≈3.0 m), however, the 3He-ions related to EAEs lost from R≈3.2-3.4 m. The MHD analysis confirms the experimental data showing that the MeV 3He ions are resonant interacting with TAE and EAE modes. a See author list of .  Ye.O. Kazakov, D. Van Eester, R. Dumont and J. Ongena, Nucl. Fusion 55 (2015) 032001  V.G. Kiptily, F.E. Cecil and S.S. Medley, Plasma Phys. Control. Fusion 48 (2006) R59–R82  D. Darrow et al. Rev. Sci. Instrum. 77 (2006) 10E701  X. Litaudon et al., Nucl. Fusion 57, 102001 (2017).