Lifter FAQ

by Evgenij Barsoukov



  • Contents:


  •  

    AC operation of Lifter

    > I am thinking: since many experiments have shown that
    > reverse polarity still produce lift force (which kI
    > found out was true with my lifter) then perhaps AC
    > will work as well? 

    It will depend on frequency you are using. You have to provide
    that ions which "started" from corona wire reach the collector before 
    you change the polarity. Otherwise you will have in wire/collector
    interval mix of positive and negative ions flying back and forth 
    and compensating each others thrust. 

    It is easy to calculate maximal frequency below which you will
    still have thrust (critical frequency). It will be 1/tau
    where tau is flight time of ion between electrodes.

    tau = d/w 
    where w is drift velocity and d is distance between electrodes

    w = k*E/d where E is voltage and k mobility coefficient (about 
    2.1 cm^2/volt*sec). So critical frequency is

    f=1/tau = k*E/d^2

    for E=40 kV and d=30mm
    we have
    f_crit=9.3*10^3 Hz (about 10kHz)

    In you increase AC frequency Above value thrust will 
    rapidly decrease. If you operate at much lower frequcy you will
    have thrust, but I guess it will be less than tha DC value at
    the same voltage.


    Effect of magnetic field on lifter

    > As long there is charge, there will be a force acting upon it, 
    described by

    > F= q(VxB)

    > where q is the charge, V is the velocity of the ion, B the applied 
    magnetic
    > field and x is the vectorial product .

    This is correct and lets calculate the force. As I mentioned in other
    message, this force will act not on corona-plasma (which is neutral)
    but on ion flux between corona wire and collector.

    First, what is B of usual permanent magnet?
    On this website there are specs for different types of mangets:
    http://www.stanfordmagnets.com/magnet.html

    As we can see, usual B is from 2 to 10 KGs (kilogauss)
    Lets use 10kGs in our calcs.

    Lets calculate q for 1 sided lifter 1. 
    Current passing the region between electrodes will be 
    where E applied voltage, k ion mobility 2.1cm^2/V*sec for positive 
    ions.
    i=w*q/d  eqn.1
    (this is strictly valid only for flat parallel electrodes, but lets 
    use it for raw assesment)
    Ion drift velocity can be calculated using w = k*E/d  eqn. 2

    See table of currents for all lifters in 
    http://jnaudin.free.fr/html/lifter4.htm) 
    For lifer 1:
    i=450uA
    V=40kV
    (for 1 side divide by 3 i=150uA)
    w=2.1cm^2/V*sec * 40 000V= 280 m/sec
    distance between collector and corona-wire 30mm, lenght of
    foil 200mm)
    charge passing between wire and collector 
    q=i*d/w; from eqn1 q=1.6*10^-8 C

    Finaly we have force applied by magnet of lenght 200mm placed near
    parallely to foil near to foil/wire gap (direction of force 
    perpendicular to foil-wire line:
    F= q(wxB)
    F = 1.6*10^-8C * 280 m/sec * 10 000 Gs = 4.5*10^-6 N

    As you can see, this force is very small comparing with 
    the vertical force exhibited by lifter 1, which is 2.8 gm* g = 0.023N

    Conclusion: 
    To see comparable to lift effect of magnet we need to use strong 
    electromagnet with B= 51 MGs (5000 times stronger than permanent 
    magnet)


    Air velocity in operating lifter

    --- In Lifters@y..., "Tim Ventura" <tventura6@a...> wrote:
    > Dear Group:

    > Anybody have any thoughts on what the average speed of the ions in 
    the air-gap is at 30kV as compared to something like the air 
    molecules in the vortex behind a propeller? The different in velocity 
    could explain a lot in terms of how such a smaller amount of the 
    medium could influence such a large amount of thrust.
    >

    There are two different velocities involved. One is drift velocity of 
    ions. It is calculated as w=k*E/d where k = 1.4 cm^2/volt*sec for 
    positive air ions, E voltage and d distance. You will get around 
    200 m/sec.

    Another is wind velocity. It will be different at different places in 
    case of Lifter, but if you assume square electrode arrangement like 
    in my mesh-proposal you can calculate it from equality of air-flow 
    force to force applied by the electric field to air. 

    Air-flow force F=w_air*dm/dt=w_air^2*D*S wher S is surface area 
    through wich air is going out and air density is D. At the other 
    hand, field force is F=i*d/k where i - current, d-distance 
    corona/collector. Resulting equation for air velocity is:

    ***************
    w_air = sqrt(D*S*i*k*d)/(D*S*k)
    ***************

    If we calculate it with:
    D=0.85 kg/m^3 (dry air, room temperature)
    i=144 uA (calculated, w/o leak)
    d=70 mm (recent lifter by Jean)
    S = 1 dm^2 (assuming flow only near to collector)

    we get around 2.9 m/sec.


    Efffect of polarity on direction of Lifter force

    Ion thrust occuring during corona discharge due to interraction of ions with medium has following steps

    1) Ionization of air molecules near electrode with high field 
    intensity near to it (the small electrode, the wire in the lifter). 
    Lets call it "emitter" for simplicity.

    2) Acceleration of ionized molecules by electric field in direction of 
    wide electrode, let's call it "collector".

    3) Transmission of momentum from accelerated molecules to outside air

    Let's apply all this 3 steps to cases with different polarity. First lets make
    "emitter" positive.
    1) We will have ionization of air to cathion-radicals or cations such 
    as N2+ N2+*. 
    2) Positive particles will be accelerated in direction of negative 
    electrode (collector)
    3) Momentum is transmitted from accelerated positive particles in 
    direction of collector.

    Now lets reverse polarity and make "emitter" negative.
    1) We will have ionization of air to anion-radicals or anions such as 
    N2- N2-*. 
    2) Negative particles will be accelerated in direction of positive 
    electrode (collector)
    3) Momentum is transmitted from accelerated negative particles in 
    direction of collector.

    As you can see, momentum is transmitted in direction of collector, therefore
    lifter force will aways be in direction of corona wire. 

    ****Thrust is applied TO the electrode which has charge carriers 
    available near to it. With other words, thrust is directed to electrode with higher field intensity near to it. Direction of thrust 
    does not depend on polarity**********

    Now, what about magnitude of thrust, depending on polarity? It depend on the ionization energy for particular positive or negative 
    ions.

    Energy for reaction O2 + e ->O2- and energy for reaction N2- e->N2+ 
    are different (the second is lower) and there is less oxigen then nitrogen in air, 
    therefore current and magnitude  of thrust with negative emitter is slightly lower 
    than that with positive emitter. This indeed has been observed by some of lifter 
    experimentalist, particularly by Cristian Marinescu
    (see http://jnaudin.free.fr/html/lfreplog.htm).

    Needless to say, this is completely independent to postion of Lifter relative to earth.


    Lifter operation in Vacuum?

    > Indeed, how can the recently patented "NASA propellantless 
    >thruster" work in space? where do the ions come form? Does this 
    >thruster only work in near earth orbit where there may be a few air 
    >molecules? If so, how much thrust can you expect to get? Must be 
    >pretty small. Maybe there is enough to get a satellite to move after 
    >a few days of activation.

    It can't. NASA uses real ionic thrusters in several probes, which
    however use balistic mechanism. As for the patent - they are just
    trying to make sure that they have stakes on that, while they
    themself say that they dont understand how it works.

    I want to make it quite clear:
    - mechanism described by my equations can operate ONLY in presence
    of a medium (without free charge carriers), which makes it an 
    interesting propulsion method in air. 
    In space amount of any medium is about 1 molecule
    per cubic centimeter, which would require distance between
    electrodes of kilometers to produce any noticeable thrust.

    - There is no experimental results in deep vacuum. The one
    result the transdimensional advertized has not since been mentioned
    or reproduced even by them. All experiments in low vacuum made in
    this group showed no thrust (due to plasma formation between 
    electrodes) as expected.

    - Results by Brown were made in time where technology to produce
    high vacuum simply did not exist. His results showed stuff like
    dependence from the distance to walls and a lot of other unexplained
    artifacts and irreproducibilities which indicate that this setup was 
    never finalized.

    - The only way how similar (but not same) mechanism could
    hypoteticaly work in vacccum involves steps of 
    1)electron emission from heated cathode
    2)interaction of accelerated electrons with walls of the chamber
    Even if this would produce some small thrust, it would do so only in 
    small chambers and is therefore useless for open space.

    Finaly, the ONLY mechanism of propelentless propulsion possible
    in vacuum is thrust by electromagnetic radiation. However, thist
    thrust is very small at given power (for example at 100W you get about
    10^-9 N (see derivation on my web-site).



     
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