HPR activities at INFN Milan. Open Questions

Transcription

1 HPR activities at INFN Milan How to qualify an HPR systems? How to compare different systems? Pressure Throughput Linear Speed Distance Number of nozzles Open Questions Transportable system for measure parameters in the HPR systems: jet force, jet profile and water jet effects

2 Possible strategy for HPR process study Measurement of Force and profile HPR effect on Nb Correlations? Cleaning Niobium oxidation? easy to be measured quantity HPR process optimization

3 Diagnostics 1. Diagnostics with load cell: I. Force measurement II. Profile measurement III. Measurements on wedged targets 2. Diagnostics using Nb sample oxidation 3. 4.

4 Hardware Nozzles: HP pump: Kärcher HD 600 C, 10 liters/min, p max 120 bar Nozzle: 0.55 mm, sapphire diaphragm, Spraying System VS120 Load cell TEDEA HUNTLEIGH mod. 505H-2M-2 max load 2kg, resolution 1 g. 28 single nozzle flow rate [g/s] y = 0.15x R 2 = pressure [bar]

5 Water Jet force vs. pump pressure Nozzle with sapphire orifice Water jet Target Nozzles Target Pressure regulator Load cell Shield Load cell Force [N] Profile at 100 bar, 103 mm from HPR axis From Bernoulli s law the expected force is 3.9 N Force [N] F = p z [mm] Pump Pressure [bar]

6 Water Jet force and profile characterization Pass through beam Momentum and energy transfer Force Profile at 100 bar, 103 mm from HPR axis erf like behaviour F, σ Force [N] Intercepted beam Measured Force Displacement z [mm] Displacement vertical speed: 2.2 mm/min Force [N] F = 3.5 N σ = 0.82 mm z [mm] Displacement F = 3.5 N σ = 0.82 mm Water Jet structure From Bernoulli s law the expected force is 3.9 N

7 Jet profiling If we approximate the jet radial dependence with a Gaussian profile, from the information of the behavior of the force vs. displacement on the target borders, we can extimate the spot dimension applying F F ( ) 0 z z z = 1+ Erf σ F 0 is the total force and σ is the spot size. The jet parameters are calculated fitting F(z) to the experimental values.

8 Spot size (σ) vs. distance σ [mm] Nozzle head position σ ( r) = r r [mm] Spot size evolution with respect to the radial position from the head axis. The nozzle exit is at 17.5 mm from the head axis.

9 Water Jet spot size vs. pump pressure σ [mm] Pump Pressure [bar]

10 Water jet interaction on a not perpendicularly surface: force measurement u p Nozzle with sapphire orifice Water jet Measured Force 2θ d o w n 30, 45, 60 Load cell Load cell transversal load rejection: Is good: about 95 %. Residual is 5%. (5g over 100g). Calibration done in a separated set-up.

11 Water Jet force vs. angle F =F ( ϑ) 0 sin Force [N] d = 17 mm Force [N] Angle [ ] d = 87 mm Angle [ ] Force [N] d = 51 mm Angle [ ] Sin dependance of the force vs. target angle d: distance nozzle - cell

12 Water Jet spot size dependence vs. target angle σ 0 σ = sin ( ϑ) d = 87 mm σ [mm] 1.0 σ [mm] d = 51 mm Angle [ ] Angle [ ] The measurements confirm the sin dependence both of force and spot size from the angle. This is important once the cleaning effect on the curved cavity surfaces will be studied.

13 Water jet power estimation The 190 Watt mean power of each of our jet corresponds, in the Gaussian approximation, to a peak power density of 250 Watt/mm 2 at 35 mm from the head axis (17 mm nozzle to surface distance)

14 Static water pressure on the cavity during HPR 6x10 7 5x10 7 Pressure Cavity Profile Pressure [Pa] 4x10 7 3x10 7 Equator 2x10 7 1x10 7 Cut-Off Tube Iris z [m] Static water pressure distribution on the cavity wall along the axis for a TESLA cavity using the jet dependences discussed before.

15 Nb oxidation as a water get profile tester Different shapes of the water jet effect on Nb samples. Left image was taken at 17 mm from the nozzle, right one at 87 mm from the nozzle. The annular footprint disappear at longer distance.

16 Nb sample oxidation: sensor? linear? 1 mm Nb oxide thickness increase

17 Monochromatic light can help to count fringes 1 mm 1 mm 1 mm 1 mm λ = 488 nm p=100 bar, σ=0.345 mm λ = 532 nm

18 From static to dynamic HP exposition p=100 bar, σ=0.345 mm 10 s 15 s 20 s mm/s 1 mm To evaluate the energy deposited by the water jet on the samples, we have performed different measurements on Nb samples up to visible changes of the surface color. In the gaussian model, the energy deposited by a fixed water jet with spot size σ 0 impinging for a time τ on a sample is equivalent to the one deposited by a moving jet at speed v σ 0 v = 2 π τ 10 s of static exposition should correspond to mm/s

19 Coloured part is oxidized? Intensity [arb. un.] Nb 3d Nb 5+ Off-center distance 0.0 mm 0.2 mm 0.4 mm 0.6 mm 0.8 mm 1.0 mm Nb 0 Intensity [arb. un.] O KLL F 1s F KLL O 1s Nb 3s Nb 3p reference (1 mm off-center) drop center C 1s Nb 3d Nb 4p -220eV Binding energy [ev] -800eV Binding energy [ev] reference (1 mm off-center) drop center O 1s F 1s F KLL Intensity [arb. un.] O 2 is increased Nb is decreased F is decreased -700eV Binding energy [ev]

20 Water Jet force and profile characterization old and new load cell set-up Easy exchangeable targets Old New Guidance for alignement

21 Long time exposition to HPR 100 bar, 17 mm nozzle-to-sample distance 20 μm 10 min 20 μm 3 mm 3 mm 20 μm 30 min 200 μm 20 μm

22 Strategy for HPR process optimization Measurement of Force and profile Long time exp. HPR effect on Nb Short time exp. Correlations? Niobium oxidation Cleaning? easy to be measured quantity HPR process optimization The force is a correct variable to be used? Oxidation can be correlated with the cleaning effect?

23 The end

24 Very preliminary data Force (N) Distance nozzle - sensor: TTF Equator Water pressure (bar) Measured data Calculated data Data are calculated as the water will loose all the energy in the impact and no energy was loss during the flight from the nozzle F = 2 A (P N pump P Atm )