by Evgenij Barsoukov
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
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,
> F= q(VxB)
> where q is the charge, V is the velocity of the ion, B the applied
> 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:
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
(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
For lifer 1:
(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
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 = 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
To see comparable to lift effect of magnet we need to use strong
electromagnet with B= 51 MGs (5000 times stronger than permanent
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
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
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
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
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
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
2) Negative particles will be accelerated in direction of positive
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
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
therefore current and magnitude of thrust with negative emitter
is slightly lower
than that with positive emitter. This indeed has been observed by some
experimentalist, particularly by Cristian Marinescu
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
- 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).