The ranked leader in this dataset holds 18 of the 204 records in scope, with the field dropping off quickly after that — fifth place holds 8 and tenth place holds 6. That drop-off means no single assignee holds a blocking position across the whole technology; most of the ranked list holds only a handful of records each. Because the ranking covers 100 companies drawn from the full record set, it should be read as the ranked leaders rather than a top-50 or top-100 industry list.

Filings rose from 3 in 2017 to a peak of 14 in 2020, then fell 36% from 2021 (14) to 2024 (9), which is the most recent year with a reasonably complete publication count. Counts for 2025 and 2026 look lower still, but that reflects the roughly 18-month lag between filing and publication rather than an actual drop in activity. Based on the complete years available, the honest read is a cooling from a 2020 peak, not a currently collapsing field.

Coating and surface deposition (C23C) is the largest single class at 24.0% of the 204 records, followed by semiconductor devices (H01L) at 17.2% and earth and rock drilling (E21B) at 15.2%. Fusion reactors specifically (G21B) account for 11.3% of records, with alloys, welding/brazing and battery materials making up smaller shares. Records commonly carry more than one class, so these figures add up to more than 100% of the record total and should not be summed.

Tungsten CVD and coating methods developed for semiconductor wafer processing and for hardfacing drill tools use much of the same deposition and bonding science needed for plasma-facing surfaces, so patents filed for those industries often read on fusion-relevant claims. Several of the most-cited records in this dataset originate from semiconductor CVD reactor patents rather than fusion-specific filings. That overlap is a useful prior-art source when drafting new claims, since it broadens the pool of documents an examiner may cite against a fusion-labelled application.

Fusion-reactor-specific claims under G21B cover only 11.3% of the 204 records, a noticeably smaller share than the coating (24.0%), semiconductor (17.2%) and drilling (15.2%) classes that dominate the dataset. That gap suggests room for claims that tie tungsten deposition or bonding methods explicitly to fusion divertor or first-wall geometry rather than to generic coating processes. Co-assignee activity is also thin, with only 10 identified pairs, indicating limited joint filing that a new entrant with a fusion-specific angle could move into without crowding an existing partnership.