Hicat a novel diagnostic for mass loss and species composition analysis
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HiCAT - a Novel Diagnostic for Mass Loss and Species Composition Analysis. L. Schmitz, P. Calderoni, Y. Tajima, A. Ying University of California, Los Angeles.

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Hicat a novel diagnostic for mass loss and species composition analysis

HiCAT- a Novel Diagnostic for Mass Loss and Species Composition Analysis

L. Schmitz, P. Calderoni, Y. Tajima, A. Ying

University of California, Los Angeles

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)


Hicat a novel diagnostic for mass loss and species composition analysis

Principle of Operation

t1 t2t3

Time Resolved Measurements of

Ablated Species Density

Line Intensity

Target

Time

PMT

PMT

Ion/Laser Beam

0.25 m Dual

Monochromator

0.25 m Dual

Monochromator

HiCAT

FiberOptics

t1t2t3

Fast Piezo Valve

Ignitrons

Ar / He

Gas

Capacitor

Bank (10 kJ)

C = 3 x 55 uF


Hicat development

PMT

PMT

HiCAT Development

Ocean Optics

compact spectrometer

Fiber Optic

Ar Ion Lines

Lens

Dual 0.27 m

Monochromators

Ar Neutral Lines

Hollow Cathode

0.5” Diameter

3 ” Length

Capacitor Bank

2 kJ

  • 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 < 1017 cm-3, kTe < 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 (0.01-5 torr) or as vacuum arc.

Z-BoxTest Chamber

(Vacuum Capable Glove Box)


Hicat a novel diagnostic for mass loss and species composition analysis

Plasma temperature and density fromspectral 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

Ar Pressure=2.5 Torr

I Ar II / IAr I

With

xi: ionization energy

EI, EII: Upper level energy for both transitions

gI, gII:Statistical weights

Aki I, Aki II : Transition probabilities

With

Pff: emission power density

Gff: Gaunt factor for free-free transitions

gI, gII:Statistical weights

Aki I, Aki II : Transition probabilities


Hicat a novel diagnostic for mass loss and species composition analysis

HiCAT Proof of Principle Tests

+ HV

-

HiCAT

Ar

Gas

Li Vapor

Heater

Li-Al

Block

ThermoCouple

Measured Lithium density compared to vapor pressure equilibrium density

(pAr= 0.3 torr)

L. Schmitz et al., J Nucl. Mat. 337-339 (2005) 1096

Plasma

Discharge


Ucla pulsed plasma research facility

UCLA Pulsed Plasma Research Facility

Z-BoxTest Chamber

(Vacuum Capable Glove Box)

20 kJ

Capacitor

Bank

Plasma

Discharge


Hicat a novel diagnostic for mass loss and species composition analysis

Z-IFE Fusion Power Plant Concept

Relative Iron Density vs. initital

free chlorine concentration

Spectral Intensity

t =200 ms

after breakdown

Na I, He I

0.14

nFe (t=200 micro-s)/nFe(t=0)

0.12

Cl II

0.1

He I

0.08

Fe I

0.06

0.04

0.02

l (nm)

0

40.00

80.00

120.00

nCl(t=0) [a.u.]

160.00

Carbon steel RTL destroyed by fusion explosion is partially vaporized and ionized. Carbon steel fragments need to be recycled from molten flibe pool.

Ferritic Fluoride(FeF3) production may cause high rate of impurities and make recycling impractical.

Experimental characteri-zation of free fluorine recombination with ferritic steel needs to be performed. We use a substitute eutectic (NaCl-MgCl2)


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