Flow electrification by cavity QED

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Flow electrification by cavity QED

• T. V. Prevenslik
• 11F, Greenburg Court
• Discovery Bay, Hong Kong

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Contents

• Historical background
• Contact electrification
• Purpose
• QED Theory
• Flow analysis
• Conclusions

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Historical background

• 1950 Streaming current ? Zeta potential
  induced by impurity ions
• 1980 Electrification ? density ionic charges
  as double layer at the wall interface
• 2001 Physiochemical corrosion-oxidation
• ... No evidence of corrosion products
• Streaming currents ? shear stress
• Source never identified

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Contact electrification
Contact and Balancing of Fermi levels
thermodynamic equilibrium Only one contact
necessary for equilibrium - independent of
materials. Experiment shows equilibrium is
reached in a single contact only for metals -
many contacts are necessary to achieve
equilibrium between metals and insulators. Some
mechanism - in addition to the balancing of Fermi
levels - is at play
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Cavity QED induced photoelectric effect

• Two-step model contact and separation
• Interface is a high frequency QED cavity that
  inhibits low frequency IR radiation from thermal
  kT energy inherent in atomic clusters.
• IR energy released concentrates to VUV levels
  in the surfaces of the metal and insulator
• Electrons are produced by the photoelectric
  effect.

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Purpose

• Extend the cavity QED induced photoelectric
  effect in the Two-step model of contact
  electrification to flow
  electrification.

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Theoretical background

• Piping system and laminar flow
• QED cavities in hydraulic oils
• Comparison of contact and flow electrification
• Available EM energy
• Photoelectric effect

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Piping system

• Hydraulic fluid is pumped in laminar flow
  through small diameter - long pipe
• Loop is closed as the fluid falls into an open
  receiving tank and pumped back to the supply
  plenum.
• Air enters the fluid in falling into
  receiving tank - usually through the pump .

Air
Air
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Laminar flow relations
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Laminar flow and QED Cavities

• Light and electron emission occurs over
  dimensions from walls less than 100 mm
• Light emission precedes electron emission -
  similar to photoelectric effect

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QED cavities in hydraulic oils

• Air clusters in flowing hydrocarbon liquids
• Tearing of oil during flow
• Tearing and QED electrification
• Source of EM energy

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Air clusters in hydraulic oil

• Oil Vapor bubbles Px lt Pvap
• Air bubbles Px lt Pair
• Air bubbles likely as Pair gtgt Pvap
• Air enters the system through the open tank
• Solubility of air in hydraulic oils is
  significant Ostwald
  coefficient 10 ? by volume
• Large air bubbles not likely by surface tension
  
• Air dissolved throughout oil as nano- clusters
  of air ( N2 and O2 molecules )

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Tearing of oil during flow

• Maximum tension theory
  Joseph, J Fluid Mech 366 (1998) 367
• Cavitation in laminar flow is explained as
  viscous shear stress produces tensile stress at
  45 to wall
• Tearing of oil occurs if nominal tensile
  stress is raised above the rupture stress of oil
  because of the stress concentration of air
  clusters
• Tearing separates oil from itself or boundary
  wall leaving an evacuated space with oil clusters
  

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Tearing and QED electrification

• Tearing produces vacuum spaces with oil
  clusters
• Spaces are a high frequency QED cavities that
  briefly suppress low frequency IR radiation from
  oil clusters.
• Suppressed IR energy loss is conserved by a
  gain to VUV levels in adjacent oil and wall
  surfaces
• Electrons are produced by the photoelectric
  effect.

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Source of EM energy

• Oil molecule has thermal kT energy
• Molecules are harmonic oscillators
• At ambient temperature, thermal kT energy is
  equivalent to the molecule emitting IR radiation

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Oscillator and IR radiation

• At T 300 K, kT0.025 eV
• Saturation at l 100 mm
• Most of IR energy in oil molecule occurs
• l gt 20 mm
• If QED cavity confines IR radiation to l lt 20 mm,
  most of thermal kT energy is suppressed

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Oil cluster formation

• Hydrostatic compression - IR uninhibited
• Hydrostatic tension - IR inhibited
• Surface tension S limits the radius R of the oil
  cluster that can be formed, R gt R0
• Heptane R0 0.4 mm

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IR energy in oil cluster
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VUV energy emitted by cluster
Cavity QED momentarily suppresses IR radiation
from cluster Conservation of energy requires the
prompt release of IR radiation Multi-IR photons
combine to VUV levels
Electrons and VIS photons produced
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Photoelectric effect
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Flow electrification

• Oil clusters and fragments in contact with
  wall separate at entrance
• IR radiation is suppressed and released as VUV
• Electrons are freed from oil
• Wall is charged negative and oil positive

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Summary

• Flow electrification occurs as oil ruptures in a
  tearing action
• Rupture takes place if the tensile stress at a
  point exceeds the pressure at which the air
  dissolved in oil, usually atmospheric pressure
• Air clusters uniformly distributed throughout
  the volume of the oil act as local stress
  concentrators for rupture
• Electron charge ? Number of oil clusters ? volume
• Electrical current is proportional to volume
  flow rate Current Charge density x volume
  flow rate
• Current not proportional to surface area of the
  wall

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Flow Analysis
Streaming current I ? Re x - flow
experiment I ? A( Px - Patm ) - electrical
analogy
NeQ replaces the flow Q Ne is the electron
density Since Ne ? NOC ? Px-1 Nc ? Px-1
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Volumetric current density
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Total current
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Conclusions

• Flow and contact electrification obey the same
  physics - Inhibited IR to VUV by cavity QED
• QED cavity is an evacuated space containing oil
  clusters that briefly forms as the oil ruptures
  and tears under tensile stress
• Tearing is governed by the tensile stress given
  by the maximum tension theory
• Cavity QED converts thermal kT energy to VUV
• The analytical I and I / Q relations derived are
  reasonable approximations of flow electrification
  data for a volume charge relation. An area charge
  relation does not correlate with the data