7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Crossover of space exploration and fusion research: spacecraft heat shields andmeteoroids in the DIII-D tokamak.
D.M. Orlov1, E.G. Kostadinova2, C.A. Mehta2, I. Bykov3, D.L. Rudakov1, R. Smirnov1 and theDIII-D team4
1
Center for Energy Research, University of California San Diego, 2 Department of Physics, AuburnUniversity, 3 General Atomics, 4 DIII-D National Fusion Facility
e-mail (speaker): dorlov@ucsd.edu
The development of materials that can withstandextreme heat flux environments is crucial for both therealization of fusion energy and the exploration of thesolar system. Testing heat shield materials is challenging
due to the lack of adequate ground testing facilities. Here,
we present a study of carbon ablation in high heat plasma
relevant to hypervelocity spacecraft entries that wasconducted in the DIII-D tokamak. We showed thatconditions in the DIII-D L-mode edge plasma canreproduce the flow velocity and high heat flux
experienced during the Galileo probe's entry into theatmosphere of Jupiter.
In this study, three types of experiments wereconducted using stationary graphite rods, porous carbon
spherical pellets, and glassy carbon spherical pellets [1].
In each case, the mass loss rates as a function of heat
flux was determined from an extensive array ofspectroscopic measurements and compared against
several semi-empirical ablation models obtained fromspacecraft flight data [2,3]. Additionally, theexperimental results for the pellet trajectories and massloss rates of the porous and glassy carbon pellets wereconfirmed using the UEDGE-DUSTT [4] simulations.
The coefficients learned from experiment and thesemi-empirical models were used in simulations toinvestigate the ablation of different carbonaceous objects
as they enter Jupiter's atmosphere. The results of thisstudy demonstrate that scaling between DIII-D
experiments, available flight data, and numerical models
can be used to optimize heat shields for future planetary
missions.

This material is based upon work supported by theU.S. Department of Energy, Office of Science, Office ofFusion Energy Sciences, using the DIII-D National
Fusion Facility, a DOE Office of Science user facility,
under Awards DE-SC0022554, DE-SC0021338,
DE-SC0023375, and DE-FC02-04ER54698.
References[1] D.M. Orlov, M.O. Hanson, J. Escalera, H. Taheri,C.N. Villareal, D.M. Zubovic, I. Bykov, E.G.
Kostadinova, D.L. Rudakov, M. Ghazinejad, “Designand Testing of Dimes Carbon Ablation Rods in theDIII-D Tokamak”, ASME 2021 International MechanicalEngineering Congress and Exposition Proceedings,
Volume 4: Advances in Aerospace Technology, Paper
No: IMECE2021-73326, V004T04A038 (2021)
https://doi.org/10.1115/IMECE2021-73326[2] C. Park “Stagnation-Region Heating Environment ofthe Galileo Probe.” Journal of Thermophysics and Heat
Transfer 23, no. 3 (2009): 417–24.
https://doi.org/10.2514/1.38712.
[3] S. Matsuyama, N. Ohnishi, A. Sasoh, and K. Sawada,“Numerical Simulation of Galileo Probe Entry Flowfieldwith Radiation and Ablation.” Journal of Thermophysics
and Heat Transfer 19, no. 1 (2005): 28–35.
https://doi.org/10.2514/1.10264.
[4] R.D. Smirnov, A.Y. Pigarov, M. Rosenberg, S.I.
Krasheninnikov, and D.A. Mendis, “Modelling ofDynamics and Transport of Carbon Dust Particles inTokamaks.” Plasma Physics and Controlled Fusion 49,
no. 4 (2007): 347–71.
https://doi.org/10.1088/0741-3335/49/4/001

Figure 1. Graphite rods with different geometries before and after exposing them to the hot plasma
from the floor of the tokamak (left). Formation of the mushroom-shaped ablation cloud around a
porous carbon spherical pellet and uncontrolled spallation of glassy carbon pellets (right).