Re: arc brilliance

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
 >
 > Original poster: "Rikard Titus by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <rikard_titus-at-hotmail-dot-com>
,
 > Tesla Coil arcs often appear more illuminated at their ends where they
 > attach to struck objects.
 > Compared with a closing section of it,a hard strike channel looks less
 > bright elsewhere.
 > Can somebody enlighten me and explain why the difference in illumination?

Greater current concentration is an obvious possibility. Even DC
arcs from a electrostatic machine are not uniformly bright, but
usually show a bright segment at the positive end, followed by a
relatively dark region, and a negative end with increasing brightness:
http://www.coe.ufrj.br/~acmq/trmspk.jpg
Stronger sparks look more uniform, but the brighter negative section
persists.
http://www.coe.ufrj.br/~acmq/bbspark.jpg
Note the straight segment at the positive end, that is always present.
Tesla coil short arcs occur in both directions in rapid sequence, and
so look similar at both ends, if the ends are similar:
http://www.coe.ufrj.br/~acmq/tesla/tefparcg.jpg
Longer arcs are actually streamers that touch a target, and are
less uniform:
http://www.coe.ufrj.br/~acmq/tesla/tefp25.jpg

Antonio Carlos M. de Queiroz