>>>> "In April 1887, Tesla began investigating what would later be called
>>>> " We now know that this device operated by emitting electrons from the
>>>> single electrode through a combination of field electron emission and
>>>> thermionic emission. Once liberated, electrons are strongly repelled by
>>>> high electric field near the electrode during negative voltage peaks >>>> from
>>>> the oscillating HV output of the Tesla Coil, generating X rays as they
>>>> collide with the glass envelope. " From:
>>>> So we know that the electrons are liberated from the end of antenna.
> Tesla was playing with Tesla coils and extremely high voltages which
> produced RF energy as a by product.