UCSD’s PISCES Program Gets an Upgrade

UC San Diego has completed a major upgrade to its PISCES plasma-materials program, integrating a high-energy ion accelerator (“POSEIDON”) directly into the existing linear plasma facility. The result is a rare capability in fusion materials science: simultaneous exposure of samples to reactor-relevant plasma conditions and neutron-like irradiation in a single controlled environment.

This combined-stress testing has been a missing piece in the global materials R&D landscape. Until now, plasma-material interactions and neutron damage were usually studied separately: plasma erosion in devices like Magnum-PSI or PISCES, and irradiation in fission reactors or spallation sources. But inside commercial reactors, first wall and divertor components will face both stressors at the same time. UCSD’s upgrade finally brings that environment into the laboratory, potentially compressing years of degradation into weeks of testing.

POSEIDON accelerates MeV-scale ions to velocities above 1,000 km/s and directs them into the same region of the plasma chamber where PISCES delivers high-heat-flux plasma. As ions enter the material, they generate displacement damage similar to what 14 MeV fusion neutrons produce. Because this damage builds up at the same time the material is being hit with plasma and thermal loading, researchers can watch microstructural changes, sputtering behavior, fuel retention, and cracking evolve under coupled conditions.

This kind of real-time interaction is something researchers have discussed for years but haven’t been able to study with enough accuracy. Early results from UCSD show that exposing materials to both stressors at once produces damage pathways that never appear when each is tested alone. These include shifts in surface chemistry, changes in defect-driven erosion behavior, and different patterns of hydrogen or helium retention—factors that could meaningfully affect how long components last in a commercial reactor.

In effect, UCSD can now run a “mini-fusion environment” in the lab, allowing rapid down-selection of tungsten alloys, ODS steels, SiC composites, and liquid-metal concepts based on how they actually behave under multiple stressors.

The strategic impact is straightforward: developers can now make materials decisions earlier, with better information, and at far lower cost. Rather than relying on fission-reactor proxy data or multi-year irradiation campaigns, engineering teams can subject candidate materials to realistic heat fluxes and neutron-like damage and rapidly iterate on coatings, cooling schemes, or structural designs. This reduces the probability of costly late-stage redesigns and increases confidence that selected materials will meet the annual ~15 dpa requirements expected in commercial power plants.

The upgrade also interacts directly with the timelines many private fusion companies are targeting for pilot plants in the early-to-mid 2030s. One of the largest unknowns in those schedules is materials durability under sustained neutron exposure. ITER, by contrast, will accumulate less than 3 dpa over its entire operational lifetime. Closing that gap requires accelerated testing. UCSD’s platform can serve as a time-compression tool, offering years of equivalent damage accumulation within months and generating the data regulators will need for licensing nuclear-class components.

This carries economic implications as well. Identifying failure modes early (cracking, embrittlement, swelling, blistering, etc) prevents the type of unplanned component failures that can stall prototype reactors for months. It also informs maintenance schedules and replacement intervals for future power plants, strengthening the credibility of long-term cost projections.

The $15M DOE-funded upgrade is explicitly structured for broad external use. Fusion developers can submit samples for testing, run joint research programs with UCSD scientists, or integrate the facility into multi-institution materials qualification pipelines. For startups without a dedicated high-heat-flux test stand or irradiation capability, this provides immediate access to data that would otherwise require building large-scale infrastructure.

The location is equally strategic. California hosts a significant portion of the U.S. fusion ecosystem, including TAE Technologies, General Atomics, and DIII-D, and UCSD’s platform now anchors a regional cluster centered on materials science, high-heat-flux testing, and plasma engineering. The lab offers opportunities for colocated work, graduate pipelines, and shared diagnostic development that can accelerate the broader West Coast fusion R&D engine.

Advanced fission programs and hybrid reactor concepts may also benefit. Any system facing combined heat, particle, and irradiation stressors can leverage this setup, making the facility relevant beyond fusion alone.

The upgraded PISCES-POSEIDON facility has the potential to strengthen the U.S. fusion materials ecosystem at a moment when commercial timelines are tightening. It offers a practical way to accelerate materials testing, reduce engineering risk, and improve the credibility of reactor lifetime projections. This synergy between academia and industry, supported by federal funding, is exactly what’s needed to accelerate fusion innovation on the materials front.