LDX Status Report
Sept 1, 2006


Full integration tests of the levitation coil (L-coil) and
levitation sensors were successfully completed during plasma
experiments conducted on July 12-14. Strain gauges installed in
the launcher-lifting apparatus measured the appropriate decrease
in floating coil weight as the levitation current increased. The
levels of noise on the optical position detectors was observed in
a variety of plasma conditions. Noise was detected from microwave
heating sources and from rapid changes in high beta plasma that
result from instabilities and cause induced voltages. Additional
shielding eliminated noise from heating systems and improved
grounding and cabling is expected to eliminate the magnetic
pickup from high beta instabilities.

The plasma experiments also allowed study of low-frequency
fluctuations, density profile modifications through controlled
neutral fueling, and several new diagnostic systems. In
particular, first measurements of density profile evolution were
obtained from the newly-installed four-channel microwave


The new lower launcher-catcher was manufactured and delivered as
promised by Hollis Line Machine Company. Fig. 1 (below) shows a
photograph of the disassembled parts of the just-received
launcher-catcher along with a cross-section schematic of the
launcher-catcher with springs compressed in both the launch and
catch configurations. After upcoming tests and installation, it
will be used to lift the floating coil into position, allow lift
off, and also reduce the force acting on the floating coil if it
should fall due to a loss-of-control event.

Fig. 1 Components of the newly received launcher-catcher system.


We are upgrading our safety interlock systems prior to our next
run with a levitated coil. During levitation, we expect a
substantial increase in plasma x-ray radiation since the supports
will no longer intercept the plasma. A new Kirk-Key interlock
system has been designed and will be installed to insure that no
one enters the experimental cell during operation. Additionally,
all LDX ECRH systems have been reprogrammed to check for the
absence of a perimeter interlock before allowing the sources to


The charging coil quench-detection-system has been upgraded.


Work on the 10.5 GHz klystron system continues--the control
program needs to be updated to include all of the interlocks and
subsystem operation checks that are needed as well as the
perimeter interlock.


Alex Zhukovsky attended the International Cryogenic Engineering
Conference 21 in Prague (CryoPrague, 2006) July 17-21 and presented
a paper titled "Retractable Helium Transfer Lines For The Floating
Fusion Magnet".

Phil Michaels is attending the Applied Superconductivity
Conference (Seattle, Aug 28-Sept 1) presenting the paper entitled
"Quench detection for the Levitated Dipole Experiment (LDX)
Charging Coil".