HiCAT- a Novel Diagnostic for Mass Loss and Species Composition Analysis Goal: Provide In-situ, real time characterization of ablated/ vaporized materials (density, species composition) Principle of HiCAT: Ablated/vaporized material is ionized/excited in a well controlled pulsed plasma discharge. The species densities and composition are determined by quantitative emission spectroscopy. Advantages compared to conventional surface analysis (Coupons, Weight loss measurements, SEM): In situ, real-time measurements with high time resolution (down to ns range depending on vapor density) Compact (1/2” diameter x 3” length) Quantitative mass loss can be determined with appropriate geometry and/or modeling) L. Schmitz, P. Calderoni, Y. Tajima, A. Ying University of California, Los Angeles

Principle of Operation  1  2  3 C = 3 x 55 uF 0.25 m Dual Monochromator 0.25 m Dual Monochromator PMT Target Ion/Laser Beam HiCAT Fast Piezo Valve Ignitrons  1  2  3 Time Line Intensity FiberOptics Capacitor Bank (10 kJ) Ar / He Gas Time Resolved Measurements of Ablated Species Density

HiCAT Development Ar Ion Lines A compact (~15 mm diam.), high power pulsed hollow cathode discharge has been developed to ionize vaporized/ablated material. High density, nearly fully ionized plasma (n < cm -3, kT e < 2 eV) with local thermodynamic equilibrium (LTE) allows simplified spectroscopic determination of plasma parameters needed to interpret materials spectra. Operation in Argon/Helium background gas or ( torr) or as vacuum arc. Ar Neutral Lines Z-BoxTest Chamber (Vacuum Capable Glove Box) Lens Fiber Optic Capacitor Bank 2 kJ Dual 0.27 m Monochromators Ocean Optics compact spectrometer PMT Hollow Cathode 0.5” Diameter 3 ” Length

Plasma temperature and density from spectral line ratio/continuum radiation (needed to evaluate ablated species like Fe, Cl, Na, Mg) Line ratio of two Ar ion lines is measured [488[nm](ArII) / 750[nm](ArII)]. Electron (plasma) temperature is given by the following two equations With x i : ionization energy E I, E II : Upper level energy for both transitions g I, g II : Statistical weights A ki I, A ki II : Transition probabilities With P ff : emission power density G ff : Gaunt factor for free-free transitions g I, g II : Statistical weights A ki I, A ki II : Transition probabilities Ar Pressure=2.5 Torr I Ar II / I Ar I

HiCAT Proof of Principle Tests Measured Lithium density compared to vapor pressure equilibrium density (p Ar = 0.3 torr) L. Schmitz et al., J Nucl. Mat (2005) 1096 ThermoCouple + HV - Heater Ar Gas Li-Al Block HiCAT Li Vapor Plasma Discharge

UCLA Pulsed Plasma Research Facility Z-BoxTest Chamber (Vacuum Capable Glove Box) Plasma Discharge 20 kJ Capacitor Bank

Relative Iron Density vs. initital free chlorine concentration n Cl (t=0) [a.u.] t =200  s after breakdown n Fe (t=200 micro-s) /n Fe (t=0) Spectral Intensity (nm) Fe I Cl II Na I, He I He I Carbon steel RTL destroyed by fusion explosion is partially vaporized and ionized. Carbon steel fragments need to be recycled from molten flibe pool. Experimental characteri- zation of free fluorine recombination with ferritic steel needs to be performed. We use a substitute eutectic (NaCl-MgCl 2 ) Ferritic Fluoride(FeF 3 ) production may cause high rate of impurities and make recycling impractical. Z-IFE Fusion Power Plant Concept