Ablation of Fusion Materials Exposed to High Heat Flux in an Electrothermal Plasma Discharge as a Simulation for Hard Disruption

Echols, J. R.; Winfrey, A. Leigh

doi:10.1007/s10894-013-9639-4

Cited by 25 publications

(8 citation statements)

References 16 publications

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“…In order to obtain the bulk flow parameters at the source exit, the stand-alone electrothermal plasma solver ETFLOW [4][5][6] has been used for the peak discharge current I = 50 kA for Lexan polycarbonate (C 16 H 14 O 3 ) [3] as the ablative capillary sleeve material for five different capillary radii, r c = 0.002, 0.00225, 0.0025, 0.00275 and 0.003 m. Ablated mass (M abl ), plasma bulk density (q), plasma pressure (P), bulk temperature (T bulk ) and plasma bulk velocity (V bulk ) at the capillary exit for the respective cases have been obtained and the Mach numbers have been calculated for the subsonic flow at the capillary exit from the obtained source exit data. Table 1 presents the relevant capillary exit data of interest, that enable us to establish scaling laws between the source radius ratio R c and the above mentioned plasma bulk parameters.…”

Section: Assessment Of Effect Of Source Capillary Radius Using Etflowmentioning

confidence: 99%

“…Disruption events expected in real-life tokamaks can deposit localized transient heat fluxes in the range of 50-60 GW/m 2 , at times even reaching a transient peak value of 80-100 GW/m 2 over a short period of time ranging from a few hundred microseconds to tens of milliseconds, resulting in evaporation of interior critical components, especially the divertor, and causing the resultant dust particulates to spread into the reactor vacuum vessel [1,3,6]. One of the recently published previous works [1] investigated high current, temperature, exit velocity and high-pressure pulsed electrothermal plasma source (PEPS) as a simulator for the source term that represents the erosion of the surfaces of various plasma facing components (PFC) and generation of aerosol particulates under a hard disruption-like condition.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Changing Source Capillary Radius on Bulk Flow Parameter Scaling Laws for Hypersonically Expanding Arc-Ablated Polycarbonate Plasma for Fusion and Space Applications

Majumdar

Banerjee

2015

J Fusion Energ

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Capillary pulsed electrothermal plasma source coupled to a linear converging-diverging nozzle was previously found to be adequate as a simulator for the supersonic bulk flow patterns of the aerosol particulates generated following a hard disruption event that damages the plasma facing components in a fusion reactor. A similar system can assume an important role in the computational studies related to space electric propulsion and electrostatic ion thrusters. Scaling laws for the prediction of bulk temperature, density, pressure, plasma bulk velocity and Mach number as a function of the axial length traversed measured from the source exit had been proposed previously for an arc-ablated polycarbonate plasma jet evolving into a vacuum chamber via the transition nozzle. In the present work, the source capillary radius has been varied and with the sectional lengths remaining fixed, the converging and diverging angles have also been varied with it, as the diverging exit Mach number was kept constant at a highhypersonic value *18. The effect of changing source capillary radius as well as the transition region geometry on the aforesaid bulk flow parameters has been studied computationally and new scaling laws have been proposed.Keywords Impurity plasma expansion Á Hypersonic expansion of arc-ablated plasma Á Changing plasma source capillary radius Á Effect of nozzle geometry on fusion particle flow

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Section: Assessment Of Effect Of Source Capillary Radius Using Etflowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Changing Source Capillary Radius on Bulk Flow Parameter Scaling Laws for Hypersonically Expanding Arc-Ablated Polycarbonate Plasma for Fusion and Space Applications

Majumdar

Banerjee

2015

J Fusion Energ

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“…Beryllium has the advantage of being a low-Z material so low risk of plasma contamination, non-reactive with hydrogenic isotopes and has good thermal conductivity [3,4] , however, its dust is toxic when ablating and expanding into the vacuum vessel of the reactor. Echols and Winfrey conducted computational work using the electrothermal plasma code ETFLOW in the ideal plasma regime for capillary discharge to simulate high heat flux deposition on materials and their ablative behavior [5] . They compared performance of beryllium and lithium at heat fluxes between 10 and 125 GW/m 2 with capillary discharge currents between 9.5 to 76 kA.…”

Section: Introductionmentioning

confidence: 99%

“…They compared performance of beryllium and lithium at heat fluxes between 10 and 125 GW/m 2 with capillary discharge currents between 9.5 to 76 kA. They reported the highest ablation for beryllium as compared to lithium [5] . The present study compares beryllium and lithium in the nonideal plasma regime for heat fluxes between 57 and 288 GW/m 2 with capillary discharge currents between 50 to 250 kA over a 120 μs pulse length.…”

Section: Introductionmentioning

confidence: 99%

Computational Investigation of Beryllium and Lithium Performance in Future Fusion Tokamaks

Elbasha

Bourham

Mohamed

2022

new n.a. exploit. and appl.

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Low-z materials are exemplary candidates in tiling critical plasma-facing components in future fusion reactors due to their low ablation rates under intense high heat fluxes especially during abnormal and hard disruption events. Beryllium and Lithium as low-z materials show good performance as plasma-facing materials in current tokamak. Future tokamaks will exhibit long duration hard disruptions, which in turn requires further investigation of plasma-facing materials, as Li and Be, to judge their performance and evaluate their erosion rates. Electrothermal plasma capillary discharges are used to simulate the high-heat flux deposition on materials to assess their erosion rates. The electrothermal plasma code ETFLOW, which is written for capillary discharges to predict the plasma parameters and erosion rates is used to simulate the high-heat flux conditions similar to expected disruption events for simulated heat fluxes from as low as ~50 to as high as ~290 GW/m2 with a reconnoitering of generating the Be and Li plasmas up to the third ionization (Br+++, Li+++). Performance of Be and Li under the lowest capillary discharge currents (50 kA and 100 kA) is almost identical, however, Li shows sharper increase in the plasma pressure, heat flux, total ablated mass and the exit velocities than Be for higher discharge currents (150, 200 and 250 kA). This huge difference between the performance of Li and Be under low and high heat fluxes can be an important issue for the future magnetic fusion reactors.

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“…However, PFMs are still subjected to the high-energy transient heat load because of the instability of plasma, such as vertical displacement events (VDEs, ~ 60 MJ m −2 , ~ 300 ms) and edge-localized modes (ELMs, ~ 1 MJ m −2 , < 0.5 ms) [12,13]. Such a high-energy density can lead to recrystallization (for deformed W materials), surface melting, ablation, cracking, and other serious irreversible damages for PFMs [14], resulting in reducing its basic physical properties and shortening its service life [15,16]. The particle irradiation from the plasma also causes some damages for PFMs.…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolutions of the W–TiC composite conducted by dual-effects from thermal shock and He-ion irradiation

et al. 2019

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Considering that tungsten (W) materials served as the plasma-facing material in the fusion reactor would be exposed to edgelocalized modes (ELMs)-like thermal shock loading accompanied with He-ion irradiation, the W-TiC composite produced with a wet-chemical method was conducted by the dual effects from the laser beam thermal shock first and He-ion irradiation later in this work. The microstructure changes of the W-TiC composite before and after two tests were characterized by scanning electron microscopy or transmission electron microscopy. After the laser beam thermal shock test, there was an obvious interface on the exposed surface of the W-TiC composite. Several main cracks and melting areas could be found nearby the interface and center, respectively. Furthermore, a mixture of tungsten oxide and TiC was easy to aggregate and form into circle areas surrounding the melting area. The thermal shock tested that W-TiC composite was then subjected to the He-ion irradiation. The typical features of fuzz structures could be detected on the surface of the W-TiC composite apart from the center of the melting area. Notably, several nano-sized He bubbles deeply distributed at grain boundaries in the melting area, owing to the grain boundary functioning as the free path for He diffusion.

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Ablation of Fusion Materials Exposed to High Heat Flux in an Electrothermal Plasma Discharge as a Simulation for Hard Disruption

Cited by 25 publications

References 16 publications

Effect of Changing Source Capillary Radius on Bulk Flow Parameter Scaling Laws for Hypersonically Expanding Arc-Ablated Polycarbonate Plasma for Fusion and Space Applications

Effect of Changing Source Capillary Radius on Bulk Flow Parameter Scaling Laws for Hypersonically Expanding Arc-Ablated Polycarbonate Plasma for Fusion and Space Applications

Computational Investigation of Beryllium and Lithium Performance in Future Fusion Tokamaks

Microstructure evolutions of the W–TiC composite conducted by dual-effects from thermal shock and He-ion irradiation

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