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Cryogenic Deuterium Pellet Injection for Enhanced Neutron Output

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Home / Mission / Site-Directed Research and Development / FY 2023 SDRD Annual Report Index / Cryogenic Deuterium Pellet Injection for Enhanced Neutron Output

Project # 23-048 | Year 2 of 3

Daniel Lowea, Trey Gebhart IIIb

aNevada National Security Site (NNSS), bOak Ridge National Lab (ORNL)
This work was done by Mission Support and Test Services, LLC, under Contract No. DE-NA0003624 with the U.S. Department of Energy, the NNSA Office of Defense Programs, and supported by the Site-Directed Research and Development Program. DOE/NV/03624–1924.

Abstract

The goal of the second year was to cool the punch system to as low as possible to help mitigate the gas expansion that is perturbing the plasma sheath formation in the Dense Plasma Focus (DPF).

Technical Approach

In order to reduce the gas expansion problem, the second stage of the cryogenic cooler was retrofitted to attach to the pellet injector piston, which will cool the piston to around 30 K. This modification was implemented at Oak Ridge National Laboratory and then sent back to the Nevada National Security Sites for fielding. The modified system was able to cool the punch to around 35 K.

Results and Technical Accomplishments

The retrofitted pellet system was attached to the Gemini DPF and fired many times. Unfortunately, the cooling of the punch did not eliminate the gas expansion problem.

Conclusions and Path Forward

Since the cooled pinch implementation did not work, we conclude that a significant amount of gas is being born in the barrel of the pellet system. The team concluded that cooling the barrel to under 30 K is a large undertaking and will pivot our idea from the pellet injection technique to the cooled inny technique.

Fast optical images of DPF plasma sheath showing (a) sheath deformation and (b) pellet location at ~4 cm below the pinch region

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