In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.
Subject: Star mode, bugle jets,etc.
Date: May 15, 4:44 pm
Poster: Richard Hull
On May 15, 4:44 pm, Richard Hull wrote:
I might not have been clear in my other message regarding the appearance and action of the various quills and jets associated with fusor operation in glow mode.
Simple early "demo fusors", (non-neutron producing), in bell jars, dessicators, etc., demand the use of a geodesic outer grid to achieve functionality.
Most early systems are run by vacuum neophytes and are typically "dirty" and often leaky systems. These are also let up to air a whole lot as the experimenter gets his or her "vacuum legs" to stabilize under them. As such, the pressures on a first pass fusor with a "coughy" pump using over worked oil tend to be in the 100-20 micron range at best. This is the realm of the bugle jet and electron "porcupine" quills as Tom Ligon and I have termed them.
In a "wheezy" first demo of this type such jets are vivid and usually shrouded in a gaseous thin nebula. At higher currents, the delicacy is often hidden and it is only upon darkening the room lights, and reducing the current that the many levels of structure can be seen. It is tough to harm such a fusor's bell jar as the mean free path is too short to allow many electrons to impinge on the walls in a condensed beam.
With a misaligned, slightly aspheric system, the bugle jet is usually singular and rarely jumps about. It is just there due to field effects arising from asymetry.
In a nearly spherical demo fusor the bugle will jump around at first during pumping as it seeks out one of maybe three or more good, electrostatically stable, inner grid openings. Once stable, the jet usually locks into a single opening.
If the pressure can be lowered into the 10 micron range and held there in a well aligned and spherical system, then the bugle slowly disappears and, at around 5-8 microns, the star mode can be seen developing out of the thin gas nebula outside of the inner grid. In a good star, no one jet appears to be any brighter than the others. Sometimes, the stars rays vary in brightness. A lot depends on cleanliness and how long the system has been kept under vacuum.
The star mode is hard to avoid in a spherical SS chambered system as the outer field is so cleanly and clearly established. With this, the inner grid only need be fairly sperical and decently centered to make easy and vivid star modes. The problem is that it is not as universally, group viewable as in the bell jar. A camera and video monitor are needed to share the inner goings-on with a crowd.