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Cryogenic Deuterium Pellet Injection for Enhanced Neutron Output of a Dense Plasma Focus

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Project #: 22-004 | Year 1 of 2

Daniel Lowe,a Michael Blasco,a Parker Winters,a Martin Palagi,a Chris Hagen,a Steve Molnar,a Larry Robbins,a Rand Kelly,a Gary Huffines,a Gio Acevedo,a Jeeno Doria,a Isaac Robinson,a Trey Gebhartb

aNorth Las Vegas (NLV); bOak Ridge National Laboratory

Executive Summary

This project aims to create a cryogenic deuterium pellet injector for use on NLV’s dense plasma focus (DPF) machine, Gemini. Several key shots were made this year and show promise for the injector. Adjustments will be made based on this year’s results in the coming project year.


The first year of this two-year project accomplished the design, fabrication, and integration of the cryogenic pellet injector to the NLV DPF machine (Gemini). Shadowgraphy and schlieren optical imaging diagnostics were coupled to the DPF chamber, as well as traditional DPF diagnostics, which include DPF current, voltage, neutron time-of-flight detectors, and total neutron yield. There were several key shots over the course of a month that shed light on both the potential of this technology as well as opportunities for improvements. One shot with the cryogenic pellet coupled to the DPF showed that the DPF did not pinch “properly,” meaning the pinch process that is the cause of the accelerator ions was significantly disturbed, yet still produced a nominal yield; this shows the promise of the technique being explored. Another shot (with better diagnostics) showed that there is significant gas flow from the cryogenic system that is being injected into the DPF chamber during the plasma flow phase, which is disrupting the plasma flow and pinch dynamics. The second year of this project will focus on improvements in the cryogenic injector, which will minimize the gas flow effect.

Figure 1. Cutaway showing pellet injector coupled with DPF system
Figure 1. Cutaway showing pellet injector coupled with DPF system


The technique explored in this year has shown promise that our designs and methodology are working. With the results of the shots so far, we will focus our attention over the coming year on minimizing gas flow into the DPF chamber to increase the yield of neutrons. Current results based on our diagnostics indicate a nominal yield already and further improvements should allow us to meet or exceed our original expected results.

Mission Benefit

Many experiments across the Nevada National Security Site (NNSS) complex rely on Gemini, and having a state-of-the-art injector allows us to continue working on our mission of Stockpile Stewardship. This technique of using the cryogenic deuterium pellet injector will allow us to enhance the overall yield of neutrons from Gemini and could potentially be applied to other DPFs across the NNSS.

This work was done by Mission Support and Test Services, LLC, under Contract No. DE-NA0003624 with the U.S. Department of Energy. DOE/NV/03624–1626.

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