Diamond Anvil Breakthrough Tests Muon Fusion Limits, But Energy Math Still Fails

The MuFusE collaboration's arXiv preprint (physics.ins-det, June 2026) describes a new large-volume diamond anvil cell achieving 19.2 mm³ deuterium-tritium samples at 933 MPa and 400 K, with 5 mm anvils and remote pneumatic controls handling 25 Ci of tritium. This is hardware development and initial characterization only—no fusion rate data, no muon beam runs reported. Methodology relied on cryogenic loading, all-metal seals, bellows compensation, and laser spectroscopy for in-situ pressure/composition checks; it is a static target design, not dynamic compression. As a preprint it lacks peer review and independent validation. Earlier μCF work (e.g., 1980s PSI and LAMPF experiments summarized in Cohen's 1989 review and Nagamine's 1990s papers) showed fusion yields capped by alpha-sticking probabilities near 0.5 %, requiring ~300 muons per fusion event—far above breakeven. High pressure can raise density and collision rates, yet the preprint ignores how muon production via accelerators still consumes ~5 GeV per muon. Connections missed by the source include parallels to failed 1980s commercial μCF hype and current high-pressure hydrogen metallization studies (e.g., Diamond et al., Nature 2020 DAC hydrogen work) that also struggle with scaling. Tritium inventory safety and optical access under beam conditions represent real engineering gains, but they do not alter the fundamental catalytic inefficiency. The apparatus advances static-target capability, yet genuine clean-energy prospects remain blocked by energy economics, not pressure limits.