Injector design for liner-on-target gas-puff experiments

Valenzuela, Jorge; Krasheninnikov, I. S.; Conti, F.; Wessel, F. J.; Fadeev, Vladimir; Narkis, J.; Ross, M. P.; Rahman, H. U.; Ruskov, E.; Beg, F. N.

doi:10.1063/1.4997429

Cited by 6 publications

(1 citation statement)

References 20 publications

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“…Hence, it is a challenge to obtain a precise capital cost for the components used in these ion-source/accelerators. Cost estimates are based on recent discussions with personnel who were involved in the development of these systems, as well as engineering estimates provided by one of us (fjw), who had responsibility for several, single-pulse IIB systems with IIB outputs in the range of, 50-2000 keV [22,25,[49][50][51]. Adjusting these cost estimates for inflation, to-date, indicates a capital cost of, C IIB ≃ 0.5 $M, and a specific cost of, C ≃ 1.4 $M MW −1 .…”

Section: Prototypical Iib Injectorsmentioning

confidence: 99%

Neutralized, intense-ion beams for fusion

Wessel,

Egly,

Rogers

2024

Plasma Phys. Control. Fusion

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- A charge- and current-neutralized, intense-ion beam (IIB) will propagate undeflected in a magnetized plasma by the $\bf{E}\times\bf{B}$, or diamagnetic, drift for a distance large compared to the beam-ion gyro-radius. This propagation occurs because of collective plasma effects when the beam-energy density is sufficient to sustain the polarization-electric field, or diamagnetic-screening currents. Our principal interest is the \exb, with $\beta = \mathcal{E}_\text{beam}/ \mathcal{E}_\text{field} < 1$. IIBs are characterized by parameters in the range: 0.1-2 MeV ion energy, 1-100 MA/m$^2$ ion-current density, and 17 - 350 kW average power produced on repetitively-pulsed systems. Multi-MW average-beam power is possible with appropriate modifications to the power supply and ion-source/accelerator. IIBs can be focused geometrically, and/or magnetically, to spot sizes of the order of a few cm's and their angular divergence is typically, $\sim$15 mRadians, suitable for long-range propagation in a vacuum beam-line. IIBs lose energy and momentum in the same manner as particles injected by a neutral-beam injector (NBIs), hence could be useful for fusion applications, including: heating, current drive, fueling, profile modifications, etc., and such applications have yet to be thoroughly studied. Summarized here are the physical principles accounting for IIB propagation; ion-source designs used to produce the IIB; and pulsed-power methods for energizing the IIB accelerator. This technology base informs scalable metrics for the ion-source/accelerator (excluding the HV power supply and interconnects) used in a conceptual injector that provides the same ion energy and injected power (1 MeV, 17 MW) as NBIs used on ITER. A comparison indicates that the IIB injector would be much smaller in size, lower cost, and have much greater efficiency, while also providing for real-time modulation of the beam energy and intensity and the use of small-diameter injection ports that could minimize fuel contamination and magnetic-field leakage between the IIB injector and tokamak.

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Section: Prototypical Iib Injectorsmentioning

confidence: 99%

Neutralized, intense-ion beams for fusion

Wessel,

Egly,

Rogers

2024

Plasma Phys. Control. Fusion

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Gated liquid scintillator detector for neutron time of flight measurements in a gas-puff Z-pinch experiment

Ruskov

Glebov

Darling

et al. 2019

Review of Scientific Instruments

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Detection of secondary D(t, n)4He neutrons produced when thin argon or krypton gas shells implode on a deuterium gas target is a very challenging task because the secondary neutron yield is a small fraction of the primary neutron yield and because the implosion is often accompanied by an intense hard X-ray burst. We built a large volume neutron time of flight (nTOF) detector using liquid scintillator (xylene solvent with small quantities of wavelength shifting PPO + bis-MSB fluors) in an attempt to increase the detection probability for secondary neutrons in our staged Z-pinch experiments at the 1 MA Zebra pulsed-power generator. Two fast, gated microchannel plate photomultiplier tubes detect the light created in 21 liters of liquid. The hard X-rays were successfully suppressed in the recorded nTOF traces, but we found no evidence of secondary neutrons. The signal quality from the primary D(d, n)3He neutrons was higher compared to the signal quality from a plastic scintillator nTOF, thus providing a more reliable estimate of the deuterium ion temperature at the pinch stagnation time. Cross-calibration with a silver activation detector enables standalone neutron yield measurement.

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Study of stability in a liner-on-target gas puff Z-pinch as a function of pre-embedded axial magnetic field

et al. 2020

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Gas puff Z-pinches are intense sources of X-rays and neutrons but are highly susceptible to the magneto-Rayleigh-Taylor instability (MRTI). MRTI mitigation is critical for optimal and reproducible yields, motivating significant attention toward various potential mitigation mechanisms. One such approach is the external application of an axial magnetic field, which will be discussed here in the context of recent experiments on the Zebra generator (1 MA, 100 ns) at the University of Nevada, Reno. In these experiments, an annular Kr gas liner is imploded onto an on-axis deuterium target with a pre-embedded axial magnetic field Bz0 ranging from 0 to 0.3 T. The effect of Bz0 on the stability of the Kr liner is evaluated with measurements of plasma radius, overall instability amplitude, and dominant instability wavelength at different times obtained from time-gated extreme ultraviolet pinhole images. It was observed that the external axial magnetic field does not affect the implosion velocity significantly and that it reduces the overall instability amplitude and the presence of short-wavelength modes, indicating improved pinch stability and reproducibility. For the highest applied Bz0=0.3 T, the stagnation radius measured via visible streak images was found to increase. These findings are consistent with experiments reported in the literature, but here, the Bz0 required for stability, Bz0=0.13 Ipk/R0 (where Ipk is the driver peak current and R0 is the initial radius), is lower. This could be attributed to the smaller load geometry, both radially and axially. Consistent with other experiments, the cause of decreased convergence cannot be explained by the additional axial magnetic pressure and remains an open question.

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Injector design for liner-on-target gas-puff experiments

Cited by 6 publications

References 20 publications

Neutralized, intense-ion beams for fusion

Neutralized, intense-ion beams for fusion

Gated liquid scintillator detector for neutron time of flight measurements in a gas-puff Z-pinch experiment

Study of stability in a liner-on-target gas puff Z-pinch as a function of pre-embedded axial magnetic field

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