[NJARC] Vacuum tube of the future is just around the corner

[antqradio at sbcglobal.net]

AlexThe illustration of the TWT: Then and Now overlooks the solenoid that was replaced early on by the Phased Periodic Magnets (PPM) shown in the "modern" TWT.  The solenoid would be located between the RF input and output ports. This is probably the single, most important, improvement in the TWT.  It reduced size, reduced mass and greatly improved efficiency, all in one fell swoop.
IIRC, a 10 watt TWT of the early 1950's vintage needed about 40 pounds of copper and iron to produce the magnetic field needed to keep the electron beam focused and prevent it from hitting the helix inside the TWT envelope.  Not to mention the additional power supply also needed to power that solenoid.Jim
      From: Alex Magoun <a.b.magoun at ieee.org>
 To: njarc at mailman.qth.net 
 Sent: Tuesday, November 24, 2015 10:50 AM
 Subject: [NJARC] Vacuum tube of the future is just around the corner
   
>From IEEE Spectrum, a nice article on traveling wave tube (aka "twit") innovations: http://bit.ly/1IdUP3m.
Alex
~~~
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IEEE History Center
at Stevens Institute of Technology
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USA

+1 732-981-3414
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