STABILITY OF HIGH VOLTAGE MODULATORS FOR NONLINEAR LOADS

Conference · Wed Oct 01 04:00:00 EDT 2003

OSTI ID:823596

PAWLEY, J C; TOOKER, J; PEAVY, J; CARY, W P; NEREM, A; HOYT, D; LOHR, J

OAK-B135 Gyrotrons have a nonlinear voltage--current characteristic such that the small signal or ac impedance changes as operational voltage and currents are reached. The ac impedance determines the stability of a voltage or current control system. this can become particularly challenging when several gyrotron are connected in parallel to a single modulator. With all gyrotrons hooked to a common ground, large current loops can be generated as well as non-canceling currents in individual coaxial lines. These inequalities can provide the required feedback impulse to start an oscillation condition in the power system for the tubes. Recent operation of two CPI 110 GHz gyrotrons in the MN class from a single modulator on DIII-D has shown instability in the power system. An oscillation in the drive current occurs at various points in the ramp up and flat top portions of the 80 kV voltage pulse with each tube drawing 40 A at full voltage. Efforts to stabilize these instabilities are presented along with some modeling and examination of the issues for gyrotron modulators.

• Research Organization: GENERAL ATOMICS (US)
• Sponsoring Organization: (US)
• DOE Contract Number: AC03-99ER54463
• OSTI ID: 823596
• Report Number(s): GA-A24487
• Country of Publication: United States
• Language: English

Related Subjects

24 POWER TRANSMISSION AND DISTRIBUTION
CONTROL SYSTEMS
DOUBLET-3 DEVICE
FEEDBACK
IMPEDANCE
INSTABILITY
MICROWAVE AMPLIFIERS
OSCILLATIONS
POWER SYSTEMS
SIMULATION
STABILITY