[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] Magnifier topics
Hi Finn
On Sun, Feb 21, 2010 at 4:23 AM, Finn Hammer <f-h@xxxx> wrote:
> David Sharpe skrev:
>
> L2 has been designed in coordination with new flux concentration
>> primary design. Once I get details fleshed out,
>>
> David,
>
> What you mention here, the flux concentration design, is new to me, and
> sounds interesting.
>
> Since the thread is in a dormant state, these last couple of days, I wonder
> if you could enlighten me about the theory behind this scheme.
>
> Eddy current concentration (Flux concentration), has been used by the
induction heating industry for over 60 years.
Several examples of the IDR driver / eddy current flux concentration
principle are listed below...
http://www.google.com/patents?id=XX9jAAAAEBAJ&pg=PA1955&dq=vacuum+tube+induction+heating+current+concentraor&source=gbs_selected_pages&cad=2#v=onepage&q=&f=false
Particularly Figure 1, in this case a solenoidal primary driving the ECFC
to heat small diameter conductive targets
http://www.google.com/patents?id=s9ZMAAAAEBAJ&pg=PA1&dq=vacuum+tube+induction+heating+current+concentraor&source=gbs_selected_pages&cad=2#v=onepage&q=&f=false
http://www.google.com/patents?id=2XdeAAAAEBAJ&pg=PA1&dq=2847651&source=gbs_selected_pages&cad=2#v=onepage&q=2847651&f=false
2847651 intrinsically validates concept is workable with pancake coils. In
my case there will be two pancake coils on either side of the ECFC
and there will be 1/4" aluminum busbar welded to the ID of current
concentrator slug. The ID of ECFC drives L2 (Tesla Coil/Driver secondary).
Secret is current is induced in area of washer is reverse direction of
exciting current (Lenz's Law). However once this sheet current hits the
radial
slot, in flows radially inward to lowest resistance path which is the ID of
the ECFC. This concentrated current now flows in same direction (in phase)
with pancake primary excitation current. At a barebones minimum most
pessimistic case, I am increasing the coupled amp-turns in to L2 coil. If
coupling was perfect, and no losses in IDR ring, boosted magnetic field
would be DOUBLED (magnetic mirror effect) with no net power increase
required.
So what is the advantages? Well looking at thelater patent it is obvious
that:
1. Highest voltages are on OD of pancakes, where radius of curvature is
maximum. That will allow HV operation with minimal leakage or flash over
hazard,
especially if a shallow "bowl" primary is used (included angle 10 deg <
x < 30 deg)
2. ID of pancakes are connected in series, effectively paralleling current
sources to plate. Yes the IDR will get warm/hot. However by wiring ID of
primaries
near ID of current concentrator, diametrically opposite of radial slot,
will dramatically reduce the voltage between the L1 primary/IDR and the L2
driver secondary. I can now run extremely close radial spacing between
L1/IDR and L2 with minimal risk of flashover, even if I am using 30kV or
more in the tank circuit.
3. I can now adjust the vertical alignment on axial centerline of the
pancake primaries to the IDR ring which gives effective control of L1
inductance,
coupling to L2 and IDR, and thereby coupled current to L2. This
methodology also allows very precise, repeatable frequency tuning control
without effecting bang size.
4. Furthermore, I can adjust vertical height of L2 independently in
relation to L1. So it is a fully adjustable primary geometry.
The key: It is a RF ground referenced CURRENT DRIVEN system, with a source
impedance < 0.1 ohm.
The only possible fly in the ointment is I may OVERCOUPLE L2 and start
getting racing sparks. If that happens, I simply decouple the system
by raising L2 as required to stop the breakdowns.
The reason I ask is, that my gut feeling says this aluminum slug is going to
> get mighty hot, due to eddy current losses.
>
Understood, but it can be force air or even water cooled in high power
applications. Also understood that it will be an additional loss term that
will be tricky to characterize.
>
> Cheers, Finn Hammer
>
>
--
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA
Sharpe's Axiom of Murphy's Law
"Physics trumps opinion!"
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla