Testing of the levitation coil (L-Coil) has begun in
preparation for levitation of the dipole magnet. The L-Coil is
a high-temperature (Bi-2223) coil that will be used to
electromagnetically support the weight of the 560 kG
superconducting dipole, or F-Coil. The purposes of the test
are (i) to demonstrate program control of the L-Coil current
using the real-time control computer, (ii) to evaluate the
overall frequency response of the levitation control system,
(iii) to establish the high-current thermal characteristics of
the L-Coil, and (iv) to demonstrate the safe operation of the
L-Coil under the conditions that will be used during
levitation. The control and interfacing wiring has been
completed; the L-Coil current has been successfully controlled
through programming of the real-time-computer; and the L-Coil
testing is proceeding as scheduled.
Construction of the laser-alignment ring is nearly completed
and ready to be mounted onto the F-Coil. This circular ring
intersects an eight-channel, redundant, laser detection system
purchased from Keyence Corp.
Components for the upper catcher frame have been received from
Hollis Machine Co. These stainless steel components will be
installed at the top and within the LDX vacuum chamber in
order to mount near-axis magnetic diagnostics and to prevent
excessive upward motion of the F-Coil during levitation.
The filament supply and water cooling connections for the 10.4
GHz, 10 kW ECRH system are being installed.
Testing was successfully completed for a method to decrease the
temperature of the high-temperature superconducting (HTS)
current lead to the L-Coil. By reducing the pressure within
the liquid nitrogen dewar to approximately 1/2 atm, the
current lead temperature decreased 6.5 deg K. This provides
extra temperature margin during operation of the
The design for the launcher-catcher system has been finalized
and drawing packages are being prepared to be sent to vendors
for quotation. This mechanical system will be used to hold the
F-Coil during pneumatic lifting of the F-Coil and to minimize
impact loads when "catching" the F-Coil at the end of
intervals of magnetic levitation.
Darren Garnier presented an invited lecture, entitled
"Controlling Interchange Instabilities in the Levitated Dipole
Experiment", at the 2006 US-Japan MHD Control Workshop held in
Naka, Japan, February 2006. While in Japan, Garnier attended
the dedication of the Mini-RT levitated ring experiment at the
University of Tokyo. The objective of the Mini-RT is to
investigate high-beta confinement in a rapidly rotating dipole
Members of the LDX Group attended the 2006 Innovative
Confinement Concepts Workshop on February 13-16 in Austin, TX.
Graduate student Eugenio Ortiz presented an invited talk,
"Effects of the hot electron interchange instability on plasma
confined in a dipolar magnetic field". Other poster
presentations were: (i) "Reconstruction of the Pressure Profile of
LDX High Beta Plasma", (ii) "Low Frequency Instability in the
Levitated Dipole Experiment", (iii) "Progress in Levitation
of the Levitated Dipole Experiment", and (iv) "Varying Electron
Cyclotron Resonance Heating to Modify Confinement on the
Levitated Dipole Experiment".
Garnier, et al., "Production and study of high-beta plasma
confined by a superconducting dipole magnet" has been accepted
for publication in the Special Issue of the Physics of
Plasmas (May, 2006).
Ortiz, et al., "Effects of the Hot Electron Interchange
Instability on Plasma Confined in a Dipolar Magnetic Field,"
submitted to J. Fusion Energy
Karim, et al., "Equilibrium Reconstruction of Anisotropic
Pressure Profile in the Levitated Dipole Experiment,"
submitted to J. Fusion Energy
Hansen, et al., "Varying Electron Cyclotron Resonance Heating
on the Levitated Dipole Experiment," submitted to J. Fusion
Copies of these presentations and pre-prints of publications
are available for download at:
An LDX exhibit is continuing at the Boston Science Museum (see LDX website).
An NPR program, "living on Earth" aired a discussion of fusion which included
a discussion about LDX.