Re: Science fiction or a wrong model again.

[Ludwik Kowalski <kowalskil@MAIL.MONTCLAIR.EDU>]

Contrary to what I wrote yesterday (see below)
the acceleration of electrons to high energies
(in a superconducting wire loop) can be possible
without a guiding external magnetic field. I just
realized that the binding energy of electrons
could be much higher than the work function.

Here is how. Electrons will start escaping but
this will result in a growing net positive
charge of the cold loop. The binding energy will
grow as the positive potential of the wire loop.
Right? For example, electrons whose kinetic
energy is below one million eV will not escape
the wire loop whose potential is two million
volts. Is it not true that only a negligible
fraction of free electrons must escape to
increase the loop potential to several million
volts?

But I would like to know what those who really
know something about superconductivity think
about the proposed setup. Please ask if you
know somebody and share what they say.

----- Original Message -----
From: Ludwik Kowalski <kowalskil@MAIL.MONTCLAIR.EDU>
Date: Tuesday, January 8, 2002 7:02 pm
Subject: Re: Science fiction or a wrong model again.

> One thing is clear, electrons will start escaping
> the wire as soon as their kinetic energies become
> larger than several eV (work function). Unless
> the loop is perfectly circular (or a solid block
> like a vacuum container) and a changing magnetic
> field is applied to keep electrons on a circular
> orbit. Under such conditions, I think, that electrons
> could be accelerated up to energies at which a gain
> per loop becomes equal to a loss per loop due to the
> synchrotron radiation. The frequency of that
> radiation will depend on the diameter of the loop.
> Will I have a chance to debate these issues in the
> general physics course? Probably not.
> Ludwik Kowalski
>
> ----- Original Message -----
> From: Ludwik Kowalski <kowalskil@MAIL.MONTCLAIR.EDU>
> Date: Tuesday, January 8, 2002 1:17 pm
> Subject: Science fiction or a wrong model again.
>
> > Jack wrote:
> >
> > > This relativistic effect has come up twice
> > > in my life. Once was in my Ph D oral exam
> > > (I answered correctly), the second was in
> > > a patent application I wrote ...
> >
> > Is this patentable, Jack? Consider the most
> > simple circuit loop: a long wire and a
> > source of emf, such as the secondary
> > winding of a transformer. The potential
> > energy gained in the source is used to
> > accelerate free electrons between collisions
> > with bound atoms of the wire. It is then
> > thermalized. But suppose that the entire
> > loop is made from a semiconducting wire. In
> > my naive model electrons would no longer
> > collide with atoms. They would circulate
> > the loop with a constant speed if the primary
> > of the transformer was off. Right or wrong?
> >
> > But with the transformer is working. Therefore
> > electrons should gain kinetic energy when the
> > emf is positive and loose it when it is
> > negative. In other words they can be accelerated,
> > like in a betatron. At f=100 Hz electrons are
> > strongly accelerated for two or three ms during
> > each cycle. That is sufficient to make a very
> > large number of round trips. Where am I wrong
> > this time?
> >
> > Suppose the average accelerating emf is 10kV.
> > How much energy will electrons gain after
> > making only 100 round trips? One million eV;
> > they will become ultarelativistic. Suppose
> > the loop also contains an element in which
> > superconductivity can somehow be destroyd at
> > the end of each accelerating cycle. This
> > element would then act as an anode in an x-ray
> > tube. By controlling the frequency, and the
> > averge accelerating emf, one can create a
> > very flexible x-ray machine. The ironless
> > transformer could be used to avoid practical
> > complications (keeping the secondary at the
> > very low temperature).
> > Ludwik Kowalski