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1. Helium release during shale deformation: Experimental validation: HELIUM RELEASE DURING SHALE DEFORMATION

   https://doi.org/10.1002/2016GC006352  

   Bauer, Stephen J.; Gardner, W. Payton; Heath, Jason E. (July 2016, Geochemistry, Geophysics, Geosystems)
2. Primordial Helium-3 Redux: The Helium Isotope Ratio of the Orion Nebula*

   https://doi.org/10.3847/1538-4357/ac6503  

   Cooke, Ryan J.; Noterdaeme, Pasquier; Johnson, James W.; Pettini, Max; Welsh, Louise; Peroux, Celine; Murphy, Michael T.; Weinberg, David H. (June 2022, The Astrophysical Journal)

   Abstract We report the first direct measurement of the helium isotope ratio, 3 He/ 4 He, outside of the Local Interstellar Cloud, as part of science-verification observations with the upgraded CRyogenic InfraRed Echelle Spectrograph. Our determination of 3 He/ 4 He is based on metastable He i * absorption along the line of sight toward Θ 2 A Ori in the Orion Nebula. We measure a value 3 He/ 4 He = (1.77 ± 0.13) × 10 −4 , which is just ∼40% above the primordial relative abundance of these isotopes, assuming the Standard Model of particle physics and cosmology, ( 3 He/ 4 He) p = (1.257 ± 0.017) × 10 −4 . We calculate a suite of galactic chemical evolution simulations to study the Galactic build up of these isotopes, using the yields from Limongi & Chieffi for stars in the mass range M = 8–100 M ⊙ and Lagarde et al. for M = 0.8–8 M ⊙ . We find that these simulations simultaneously reproduce the Orion and protosolar 3 He/ 4 He values if the calculations are initialized with a primordial ratio 3 He / 4 He p = ( 1.043 ± 0.089 ) × 10 − 4 . Even though the quoted error does not include the model uncertainty, this determination agrees with the Standard Model value to within ∼2 σ . We also use the present-day Galactic abundance of deuterium (D/H), helium (He/H), and 3 He/ 4 He to infer an empirical limit on the primordial 3 He abundance, 3 He / H p ≤ ( 1.09 ± 0.18 ) × 10 − 5 , which also agrees with the Standard Model value. We point out that it is becoming increasingly difficult to explain the discrepant primordial 7 Li/H abundance with nonstandard physics, without breaking the remarkable simultaneous agreement of three primordial element ratios (D/H, 4 He/H, and 3 He/ 4 He) with the Standard Model values. 

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3. Pulsed helium droplet beams

   https://doi.org/10.1016/j.cplett.2018.01.035  

   Verma, Deepak; Vilesov, Andrey F. (February 2018, Chemical Physics Letters)
4. The 3-Helium Problem

   Balser, D.; Bania, T. (January 2020, American Astronomical Society meeting #235)

   The light element 3He is produced in copious amounts during the first three minutes after the Big Bang. The 3He abundance is then modified primarily by nucleosynthesis in stars, whereby low-mass stars (< 2 solar masses) are expected to produce 3He due to the astration of deuterium. The higher temperatues in more massive stars fuse 3He completely into 4He thus destroying 3He. Measurements of 3He are made via observations of the hyperfine transition of 3He+ at 3.46 cm. Observations of 3He+ in HII regions located throughout the Milky Way disk reveal very little variation in the 3He/H abundance ratio — the "3He Plateau", indicating that the net effect of 3He production in stars is negligible. This is in contrast to much higher 3He/H abundance ratios found in some planetary nebula (PNe). This discrepancy is known as the "3He Problem." One solution to this problem is that thermohaline mixing occurs just above the hydrogen-burning shell to process 3-Helium: 3He(3He, 2p)4He. Thermohaline mixing is a double-diffusive instability that occurs in oceans and is also called thermohaline convection. We discuss how more accurate observations of the 3He/H abundance ratio can constrain stellar evolution models that include thermohaline mixing. 

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5. Properties of Daily Helium Fluxes

   https://doi.org/10.1103/PhysRevLett.128.231102  

   Aguilar, M.; Cavasonza, L. Ali; Ambrosi, G.; Arruda, L.; Attig, N.; Barao, F.; Barrin, L.; Bartoloni, A.; Başeğmez-du Pree, S.; Battiston, R.; et al (June 2022, Physical Review Letters)