Progress on UCLA MTOR Film Flow Experiments for ALIST (Nov. 2002- April 2003)

1. Progress on UCLA MTOR Film Flow Experiments for ALIST(Nov. 2002- April 2003) Presented by Alice Ying M. Abdou, N. Morley, T. Sketchley, J. Burris, M. Narula April 7, 2003 APEX Meeting Grand Canyon, AZ

2. Experimental Investigation now Focused on Film Flow Characteristics with Conducting Walls • Most likely the electrical insulator coating would not be available in the next few years. In addition, • Film in insulated chute appeared feasible passing through the NSTX-like steady state 2-D field gradients (toroidal and surface normal), except additional MHD pressure drop • There was a need to add the 3rd component field (poloidal field) to complete the exploratory assessment (steady state). However, the field magnitude is relatively low (thus its effect may not be significant) •  Would revisit this effect if the result of the conducting chute film flow shows unfavorable.

3. Initial exploration: Ga flows upwardly from inboard (high field) to outboard (low field)

4. MTOR experimental set-up for NSTX film flow concept evaluation The concept: NSTX Lithium Free Surface Module (ORNL) Experimental Investigation Tailored for Concept Evaluation

5. Stainless steel walls conducting channel (5 cm wide/45 cm long) steel wall thickness: 0.5 mm The entry nozzle profile Inlet nozzle assembly ‘c’ is the conductance ratio; a = channel half-width Nozzle Inlet manifold with perforated plate for uniform flow distribution Outlet assembly with cover plate to prevent Ga overshoot Electrically Conducting Walls Test Article Fabricated from Stainless Steel

6. Jet experimental setup Ga Film flow experimental setup Achieving prototypical NSXT magnetic fields configuration using GaInSn for Li simulation 1. flux concentrator with taper block for gradient toroidal field simulation 2. Permanent magnet placed near the outlet for gradient surface normal field simulation

7. steel wall thickness: 0.5 mm Drain section Inlet Nozzle /inlet manifold Permanent magnets Outlet Stainless Steel Conducting-Walls Test Article with Permanent Magnets

8. x: axial (flow direction) y: toroidal z: normal Flow direction 34 cm outboard Flow direction inboard Permanent magnets (2) MTOR field vector plot to illustrate field direction and relative strength Conducting-Walls Film Flow Test Article (schematic) and MTOR Magnetic Fields

9. Near the inlet, the MHD effect is the strongest, while the turbulence is quickly damped and the turbulent structures are markedly elongated in the magnetic field direction. • The stretched 2-D turbulent structures begin to break down as Ga proceeds to the lower field regions (outboard). MHD LM (GaInSn) Film Flow Characteristics(Gradient Toroidal Fields)

10. Inlet velocity 3 m/s Stretched 2-D rolling waves 2-D turbulent structures broken down 20 19 18 17 16 15 14 13 12 11 10 9 Field magnitudes vs distance LM Film Flow Under Gradient Toroidal Fields: Movie with Better Lighting Flow

11. 2-D rolling waves broken down as field drops 3 m/s Angular momentum normal to B field being destroyed over a time scale of 4 ( = 0.0017 s ) At higher velocity, 2D rolling waves persist to lower fields. 4.4 m/s Toroidal field Stronger MHD Present as Velocity Increases (gradient toroidal field only)

12. No field Invert image Gradient toroidal field Invert image Invert image Surface normal field Effect of Field Orientation on LM MHD (3 m/s)

13. Distinct wavy flow pattern appeared/observed as magnet field configuration becomes complicated(inlet velocity 3 m/s) 2-D stretched- rolling waves Ga flow appears thickened/frozen Surface normal field applied at ~18 cm downstream and increases from 0.15 T to 0.32 T (at 30.87 cm downstream) and 0T thereafter(see slide #3 for field values) Significant damping force from surface normal field MHD LM (GaInSn) Film Flow Characteristics(Surface Normal with/without Gradient Toroidal Fields) inboard Outboard 0 4 8 12 16 20 24 2832(cm)

14. Unit: mm; inlet ga alloy velocity = 2.0 m/s 3.97 3.42 5.89 2.32 3.0 8.3 Surface normal field applied • 7 ultrasonic film height transducers used • Speed of sound for Ga alloy measured 2740 m/s • Speed of sound for stainless steel measured 5400 m/s (a thicker and larger plate needed to differentiate time-of-flight) • Ultrasonic transducers mounted directly touching Ga alloy • Ga alloy oxidation results in no signal (cleaned Ga alloy) • Turbulent fluctuation of liquid surface causes energy to be lost before the wave reflects back to sensor (lose of signal) • Shown difficulties to use for high velocities such as 3 m/s Ultrasonic Film Height Transducers • Only one data point obtained and showed additional MHD effect from added gradient toroidal field; film thickness increased by a factor 2

15. Principles of Operation The capacitive reactance is proportional to the spacing of a parallel-plate capacitor, which is made up of the probe and an electrically conductive measuring surface (Ga surface) As the distance varies due to the change of the film height, the capacitive reactance varies accordingly probe gap Capacitance Probe Film Height Measurements • As a mean to measure film height at higher velocities(> 2.5 m/s) Results using in-house capactive probe have obtained for static films However, those probes were acquired to measure sub- minimeter gaps encountered in thermomechanics experiments. They are difficult to implement in the ga film flow runs (which needs probe installed near touching the free surface)

16. Exploratory studies for flowing liquid metal divertor options for ALIST NSTX in MTOR facility- A. Ying et al. • Contents • 0. Introduction • I. Background Information (FLOW3D Numerical Simulation results to show why experimental study is critical) • II. MTOR Facility- Flux concentrator/Engineering Scaling and Stage-one Objectives of MTOR Experiments • III. Characterization of Liquid Metal Jets Under Gradient Transverse Fields • III.1 Introduction /Typical Jet Behavior without MHD, Literature Review of MHD-Jet Studies • III.2 Experimental Studies in MTOR • III.3 Experimental Results • IV. Film Flow Characteristics Under Complex Gradient Fields • IV.1 Introduction /Typical Film Behavior without MHD, Literature Review of MHD-Film Studies • IV.2 Experimental Studies in MTOR • IV.3 Experimental Results and Analysis • V. Summary and Next-step Plan