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General => General Technical Chat => Topic started by: dadler on May 02, 2015, 07:00:25 pm

Title: Visible return current
Post by: dadler on May 02, 2015, 07:00:25 pm
http://www.sigcon.com/Pubs/news/8_08.htm (http://www.sigcon.com/Pubs/news/8_08.htm)

I am sure some of you have seen this before, as it's on Dr. Howard Johnson's site.

The pictures are great.
Title: Re: Visible return current
Post by: Zero999 on May 03, 2015, 01:46:37 pm
I'm not convinced this is an accurate demonstration of this because the breakdown voltage of the spark gaps will dominate the inductance.

The arc only tracks the inductor because the intense electric field produced by it will be coupled to the spark gap and reduce its breakdown voltage substantially.
Title: Re: Visible return current
Post by: SArepairman on May 04, 2015, 10:25:38 pm
mikes electric stuff did another take on this by using a contact fluxgate magnetometer, LED and long exposure time. its on youtube

the brighter the LED = more current. you just use the fgm like a wand and scan the ground plane, and it looks like a glowly blur of current magnitude (and you can even do direction (using diff color lights), since the FGM will tell you the current direction by its sign.
Title: Re: Visible return current
Post by: T3sl4co1l on May 05, 2015, 12:54:36 am
A high voltage pulse will exhibit the same path due to electrostatic induction.  It's not wrong, because in a linear system, electric and magnetic fields will be correct at DC as well as at HF (as transmission line).  But it's not fair to say it's the electromagnetic path taken; the sparks jump due to electric field only, and thereafter can only be pushed by magnetic fields.  They won't jump between corners and reorganize.

Tim