[show abstract][hide abstract] ABSTRACT: In this article we present the design and test results of the most powerful, fast linear transformer driver (LTD) stage developed to date. This 1-MA LTD stage consists of 40 parallel RLC (resistor R, inductor L, and capacitor C) circuits called ``bricks'' that are triggered simultaneously; it is able to deliver ˜1MA current pulse with a rise time of ˜100ns into the ˜0.1-Ohm matched load. The electrical behavior of the stage can be predicted by using a simple RLC circuit, thus simplifying the designing of various LTD-based accelerators. Five 1-MA LTD stages assembled in series into a module have been successfully tested with both resistive and vacuum electron-beam diode loads.
Physical Review Special Topics-accelerators and Beams - PHYS REV SPEC TOP-AC. 01/2009; 12(5).
[show abstract][hide abstract] ABSTRACT: Summary form only given. A module consisting of five 100 GW Fast LTD cavities stacked in series was tested with e-beam diode load to study how a number of cavities behave and add their energy, power and voltage output in a voltage adder configuration assembly. In this report we present the design of the module and diode, and compare test results with simulations.
[show abstract][hide abstract] ABSTRACT: Summary form only given. In the report, we present the new super fast LTD prototype which delivers a 75 ns FWHM voltage pulse into a -0.5-0.6 Ohm matched load at ~20 GW power. The stage is designed without of peaking capacitors, it includes 32 GA35436 (8 nF, 100 kV) storage capacitors, 16 spark gap switches and magnetic core with reduced thickness of the tape (50 mum) to reduce the current losses. This stage prototype was specifically designed with an hemispherical vessel to operate with compressed gas (SF6, SF6/dry air mixtures, and pure dry air) up to 6 ata pressure, as well as with transformer oil. Test results of the stage prototype will be given and compared with numerical simulation.
[show abstract][hide abstract] ABSTRACT: Summary form only given. Sandia Laboratories is actively pursuing the development of new accelerators based on the novice technology of linear transformer driver (LTD). LTD based drivers are considered for many applications including future very high current Z-pinch ICF (inertial confinement fusion) drivers like ZX and Z-pinch IFE (inertial fusion energy). The high current LTD driver experimental research is concentrated on two aspects: first, to study the repetition rate capabilities, life time and jitter of the LTD cavities; and second to study how a number of cavities behave and add their energy, power and voltage output in a voltage adder configuration assembly. The repetition rate and life time studies are being done in the Sandia high current LTD laboratory utilizing a prototype 500-kA, 100-kV LTD cavity. The voltage adder experiments are being conducted jointly at the high current electronic institute (HCEI) in Tomsk, Russia where a number of 1-MA cavities are being built under Sandia contract. Experimental arrangements and first experimental results are presented and analyzed.
[show abstract][hide abstract] ABSTRACT: Fast LTD technology looks promising for making the pulsed power generators for some applications more compact and less expensive because it does not need any pulse forming lines to produce nanosecond output pulses. In the report we present the 1 MV generator that is being produced to demonstrate the technology capability. The generator is designed to deliver a 1 MV, 125 kA, /spl sim/50 ns width at 80% of peak amplitude pulse to the /spl sim/8 Ohm vacuum diode. The stored energy of the generator is 14 kJ, the footprint /spl sim/ 2 m/sup 2/.
Pulsed Power Conference, 2003. Digest of Technical Papers. PPC-2003. 14th IEEE International; 07/2003
[show abstract][hide abstract] ABSTRACT: Primary storages based on a linear transformer scheme were
developed long ago. In this scheme, the secondary turn only
has to be insulated from the high output voltage. Seven years
ago at the High Current Electronics Institute (HCEI) a primary
storage based on a linear transformer scheme and called the
Linear Transformer Driver (LTD) stage was designed. In LTD stages,
the primary turn, the storage capacitors with the switches,
the core, and the outer conductor of the secondary turn are
integrated into the stage cavity representing one separate building
block of the primary storage. The body of the LTD cavity keeps
ground potential during the shot allowing us to assemble them
in series or in parallel depending on load requirements. Such
flexibility of the storage structure and high output power of
the LTD stages allows us to replace for some applications the
traditional water line technology with LTD-based primary storages
that are connected directly to the load (Direct Drive
Scheme—DDS). In this article, we present the design of
several LTD stages developed at HCEI and give examples of
high-power energy storages produced by using the LTD technology.
[show abstract][hide abstract] ABSTRACT: LTD stages are designed to be used as a primary energy storage in high power pulsed generators. Previously the LTD stages with the current rise time of 1000 ns and 450 ns were reported. Present report describes the design and test results of the LTD stage that provides ∼200 kA rising in 100 ns in the matched ∼0.4 Ohm load.
Pulsed Power Plasma Science, 2001. PPPS-2001. Digest of Technical Papers; 02/2001
[show abstract][hide abstract] ABSTRACT: Summary form only given. LTD stages are designed to be used as primary storage of pulsed power generators. Their main difference compared to the Marx scheme is ground potential on the stage housing during the shot. This reduces the dimensions of the storage, makes it flexible for reconstruction, simplifies the assembling and maintenance. Other advantage of the grounded housing is the possibility to trigger each stage from the external trigger circuit. This allows to distribute the current flow inside the stage in multiple parallel channels, reducing the equivalent inductance and the current rise time. Previously LTD stages providing 1000 ns and 400 ns current rise time were reported (Bastrikov et al., 1997, Kim et al., 1999). This report presents the design and test results of a fast LTD stage with 100 ns current rise time
Electroencephalography and Clinical Neurophysiology/Electromyography and Motor Control 01/2001;
[show abstract][hide abstract] ABSTRACT: In experiments on GIT4, a scheme with the load connected upstream
from the plasma opening switch (POS) was investigated. The load was
connected to the generator output through the surface self-breaking
switch. The current switching into the different inductive loads was
tested. It was found that the time the POS is open depends on the value
of the load inductance. It was demonstrated also that surface
self-breaking switch can be applied for switching currents rising at
Pulsed Power Conference, 1999. Digest of Technical Papers. 12th IEEE International; 02/1999
[show abstract][hide abstract] ABSTRACT: Experiments have been performed on the GIT-4 generator with a plasma opening switch to study the operation of a circuit connecting
the load and the switch through an untriggered spark gap depending for its operation on a discharge over the surface of a
dielectric in vacuum. The current switching into inductive loads of different inductance was investigated. The dependence
of the time the switch is open on load inductance has been found. It has been demonstrated that the surface-discharge spark
gap can be used at current rise rates of up to ∼21013 A/s.
[show abstract][hide abstract] ABSTRACT: A circuit is proposed for increasing the power and voltage across the load in a generator based on a line pulse transformer.
The power is amplified by series connection of plasma opening switches between the transformer sections. A numerical analysis
has been performed for the generator circuit. The results of experiments on determination of the characteristics required
for realization of the proposed opening switch circuit are reported.
[show abstract][hide abstract] ABSTRACT: Experiments on switching current into an inductive load with a plasma opening switch have been performed. The geometry of
the transitory region between the plasma opening switch and the load for which complete switching of current is possible has
been determined experimentally. It has been demonstrated that a decrease in the electrode gap spacing in the transmission
line results in shunting of the load and reclosure of the switch.
[show abstract][hide abstract] ABSTRACT: A description is given of sections of a linear pulse transformer (a linear transformer driver, LTD) intended for use as a
fast primary storage device in pulse generators with intermediate inductive energy storage. The results of tests of LTDs consisting
of 3 and 10 series-connected sections are given. Results are described for experiments on coupling energy out of such a generator
using a plasma opening switch.
[show abstract][hide abstract] ABSTRACT: The main advantage of the primary storage based on linear transformer scheme is the ground potential on the capacitor bodies during the shot, allowing exclusion of the total output voltage insulation of the highest stages, and to trigger all the stages simultaneously by using an external trigger pulse. The problem was to build a fast linear transformer driver (LTD), providing both high efficiency of energy transfer into the secondary turn and the current rise time below /spl sim/1 CLs, because of relatively high inductance of the caps and the switches. The key elements of the LTD described below are the HAEFELY capacitors (75 kV, 5.65 /spl mu/F, 13 nH, 40 mOhm, or 90 kV, 3.95 /spl mu/F, 10 nH, 13 mOhm) and the multi gap, multi channel spark switches developed at HCEI for SYRINX project (90 kV, 0.7 MA, 8.5 nH). This LTD was designed as an alternative to the Marx generator in order to improve the performance of the IES technology in the direct drive approach where the only unit providing power multiplication on the load is the POS. The LTD was designed as a single stage with two HAEFELY caps in parallel. The authors describe a 75 kV LTD stage with oil insulation and a 90 kV LTD stage with SF/sub 6/ insulation.
Pulsed Power Conference, 1997. Digest of Technical Papers. 1997 11th IEEE International; 01/1997
[show abstract][hide abstract] ABSTRACT: We outline the design concept for low-inductance high-current spark modules at a voltage level of 100 kV and a current of
1 MA. We present the results of an investigation of the switching and operating characteristics of multichannel, multigap
spark modules as a function of the design and the shape and amplitude of the beam pulse. We give a description of the designs
and parameters of the developed types of spark modules.
[show abstract][hide abstract] ABSTRACT: A pulsed generator with a power of 0.1 TW, an amplitude of up to 2
MV and ~1.5 nsec rise time is described. A Marx generator charges a low
inductive capacitor (1.8 nF) and a radial line (0.9 nF) to a voltage of
~2 MV in 200 nsec. At the peak voltage, a water switch breaks down at
the center of the radial line resulting in a ~2.5 MV voltage pulse at
the end of the line. This pulse propagates along the oil-insulated line.
The line is connected to an oil-filled peaking switch with a metal
diaphragm, which reduces the transfer capacitance of the discharge gap
to 5 pF in order to match the radial line with a load being connected to
the switch output. A crowbar switch may be used for operation in the
short-pulse mode. A pulse with a width of up to 20 nsec has been
generated on a matched load equivalent
Pulsed Power Conference, 1995. Digest of Technical Papers., Tenth IEEE International; 08/1995 · 0.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: Summary form only given. A second POS (plasma opening switch) stage is proposed to increase the output pulse parameters of the GIT-4 generator, provided the first POS stage gives rapid current input (in about 100 ns) in the second POS stage. The latter can be designed with diminished inner electrode diameter to achieve rapid opening. Experiments have shown that the dRs/dt (where RS is the switch resistance) of the second stage is about 100 times higher than that of the first stage. To measure the output voltage two techniques were used: a 3-m-long vacuum coaxial line (VCL) and p-i-n-diode X-ray measurements. It was found that the voltage pulse on the 30-Ω electron diode load rises in about 10 ns up to 4 (p-i-n) to 5 (VCL) MV
[show abstract][hide abstract] ABSTRACT: Summary form only. The results of an investigation of ion and electron flows in a coaxial microsecond plasma opening switch (POS) are given. A 1-μs front duration POS with outer and inner electrodes with diameters of 210 mm and 75 mm, respectively, switched a 1-MA pulse during 0.1 μs to a 120-cm-long short-circuited coaxial line with matching diameters. The polarity of the inner electrode was negative. The plasma of the POS was injected from the outer electrode by 32 plasma guns of capillary type. The typical POS voltage was 0.9-1.2 MV. The calculated energy losses in the POS during the switching phase reached 0.1-0.15 MJ. The location and distribution of the heat absorbed along the POS electrodes were determined. Measurements of electron flow showed that heat energy absorbed by the POS anode (which made up 30-40% of the total energy losses in the POS) did not affect the flow. Nuclear activation measurements showed that the energy of the convergent proton flow was in good agreement with the voltage generated in the POS and that almost all of the energy input in the inner electrode could be provided by intense ion flow
Plasma Science, 1989. IEEE Conference Record - Abstracts., 1989 IEEE International Conference on; 06/1989