Linear transformer driver: Difference between revisions

Revision as of 22:10, 18 April 2014

Revision as of 07:03, 12 October 2014

Line 1:

{{Context|date=AprilOctober 2010}}

TheA '''linear transformer driver''' (LTD) is aan low-voltageannular variant[[Series ofand theparallel [[inductive voltagecircuits#Parallel addercircuits|parallel]] (IVA)connection technologyof firstswitches applied atand [[Arzamas-16capacitor]]s (nowdesigned to deliver rapid high [[SarovPower (physics)|power]]), Russiapulses. andThe laterLTD was designed at the Institute forof high-currentHigh electronicsCurrent Electronics ([[IHCE]]) in [[Tomsk]], Russia. The [[Hermes III]] gamma-ray generator at [[Sandia National Laboratories]]LTD is another examplecapable of anproducing IVAhigh design. In IVA designscurrent, each megavolt “stage” is added in seriesup to the1 proceedingmegaamp stage(10⁶ usingamps), largepulses ironwith coresa to[[risetime]] inductivelyof isolateless thethan individual100 stagesns. This conceptis permitsan aimprovement veryover large[[Marx voltagegenerator]] tobased be[[pulsed generatedpower]] bydevices addingwhich therequire voltagepulse fromcompression eachto stageachieve insuch fast seriesrisetimes. HermesIt IIIis deliversbeing aconsidered peakas voltagea ofdriver 20 MV to anfor [[electron beamz-pinch]] loadedbased to[[inertial theconfinement devicefusion]].

==LTDs at Sandia National Laboratories==

LTDs use the same IVA concept but use low voltage components. Each individual cavity (similar to an IVA stage) operates at an [[Electric circuit|open circuit]] voltage typically in the range of 100 kV to 200 kV. There is no high-voltage switching or pulse forming. An LTD cavity is composed of a number of "bricks" connected in parallel. The choice of the brick [[capacitance]], [[Electrical resistance|resistance]], and [[inductance]] defines the base pulse shape of the brick, and therefore the pulse shape and current of the cavity and, finally, the module. There are no further pulse-forming components. The efficiency of energy coupling from the [[storage capacitor]]s to the load is very high, typically over 60–70%.

[[Sandia National LaboratoriesLaboratory]] in Albuquerque, NM is currently investigating a z-pinch as a possible ignition source for inertial confinement fusion. On its "[[Z machine]]", Sandia can achieve dense, high temperature plasmas by firing fast, 100-nanosecond current pulses exceeding 20 million amps through hundreds of tungsten wires with diameters on the order of tens of micrometres. A driver based on theThe LTD concept is currently being investigated as a driver for the next generation of high power accelerators.

Pulse width and pulse shape are simple design choices for LTD generators. By tailoring the capacitors and switches one can generate a wide range of electrical pulse shapes.

Sandia's roadmap includes another future Z machine version called ZN (Z Neutron) to test higher yields in fusion power and automation systems. ZN is planned to give between 20 and 30 MJ of hydrogen fusion power with a shot per hour thanks to Russian Linear Transformer Driver (LTD) replacing the current Marx generators.<ref>[http://www.sandia.gov/LabNews/070427.html Rapid-fire pulse brings Sandia’s Z method closer to goal of developing high-yield fusion reactor], Sandia's press release (April 27 , 2007).</ref> After 8 to 10 years of operation, ZN would become a transmutation pilot plant capable of a fusion shot every 100 seconds.<ref>[http://www.prod.sandia.gov/cgi-bin/techlib/access-control.pl/2006/067148.pdf Z-Inertial Fusion Energy: Power Plant Final Report FY 2006], Sandia Report SAND2006-7148 (October 2006).</ref>

Additionally, LTDs provide a range of flexible [[particle accelerator|accelerator]] designs. Adding bricks in parallel per cavity increases the current per cavity. Adding cavities in series increases the voltage per module. Adding modules in parallel gives the final accelerator current. LTDs have been built with pulse widths as short as ~ 50 ns and as long as ~ 1 µs. LTD generators have achieved voltages greater than 700 kV. LTD drivers have reached currents greater than 1 MA. New LTD drivers are under construction at many laboratories and the performance figures quoted above are subject to change.

Fundamentally, LTDs provide a new flexible & compact pulsed-power architecture. LTDs are particularly suited for high-power low-energy applications such as [[radiography]] sources, [[x-ray generator]]s, and [[gamma-ray generator]]s.

==Technical discussion==

The simplest electrical description of an LTD cavity is shown in Fig. 1 below.

==LTDs at SANDIA NATIONAL LABORATORIES==

[[Sandia National Laboratories]] in Albuquerque, NM is currently investigating a z-pinch as a possible ignition source for inertial confinement fusion. On its "[[Z machine]]", Sandia can achieve dense, high temperature plasmas by firing fast, 100-nanosecond current pulses exceeding 20 million amps through hundreds of tungsten wires with diameters on the order of tens of micrometres. A driver based on the LTD concept is currently being investigated for the next generation of high power accelerators.

Sandia's roadmap includes another future Z machine version called ZN (Z Neutron) to test higher yields in fusion power and automation systems. ZN is planned to give between 20 and 30 MJ of hydrogen fusion power with a shot per hour thanks to Russian Linear Transformer Driver (LTD) replacing the current Marx generators.<ref>[http://www.sandia.gov/LabNews/070427.html Rapid-fire pulse brings Sandia’s Z method closer to goal of developing high-yield fusion reactor], Sandia's press release (April 27, 2007).</ref> After 8 to 10 years of operation, ZN would become a transmutation pilot plant capable of a fusion shot every 100 seconds.<ref>[http://www.prod.sandia.gov/cgi-bin/techlib/access-control.pl/2006/067148.pdf Z-Inertial Fusion Energy: Power Plant Final Report FY 2006], Sandia Report SAND2006-7148 (October 2006).</ref>

The next step planned would be the Z-IFE (Z-inertial fusion energy) test facility, the first true z-pinch driven prototype fusion power plant. It is suggested it would integrate Sandia's latest designs using LTDs. Sandia labs recently proposed a conceptual 1 petawatt (10¹⁵ watts) LTD Z-pinch power plant, where the electric discharge would reach 70 million amperes.<ref>W.A. Stygar ''et al.'', [http://www.sandia.gov/pulsedpower/prog_cap/pub_papers/accelerator_architecture_PRSTAB_2007.pdf Architecture of petawatt-class z-pinch accelerators] (October 2007).</ref>