100 ns current rise time LTD stage

215

128

We have developed an accelerator architecture that can serve as the basis of the design of petawatt-class z-pinch drivers. The architecture has been applied to the design of two z-pinch accelerators, each of which can be contained within a 104-m-diameter cylindrical tank. One accelerator is driven by slow ( 1 s) Marx generators, which are a mature technology but which necessitate significant pulse compression to achieve the short pulses ( 1 s) required to drive z pinches. The other is powered by linear transformer drivers (LTDs), which are less mature but produce much shorter pulses than conventional Marxes. Consequently, an LTD-driven accelerator promises to be (at a given pinch current and implosion time) more efficient and reliable. The Marx-driven accelerator produces a peak electrical power of 500 TW and includes the following components: (i) 300 Marx generators that comprise a total of 1:8 10 4 capacitors, store 98 MJ, and erect to 5 MV; (ii) 600 water-dielectric triplate intermediate-store transmission lines, which also serve as pulse-forming lines; (iii) 600 5-MV laser-triggered gas switches; (iv) three monolithic radial-transmission-line impedance transformers, with triplate geometries and exponential impedance profiles; (v) a 6-level 5.5-m-diameter 15-MV vacuum insulator stack; (vi) six magnetically insulated vacuum transmission lines (MITLs); and (vii) a triple-post-hole vacuum convolute that adds the output currents of the six MITLs, and delivers the combined current to a z-pinch load. The accelerator delivers an effective peak current of 52 MA to a 10-mm-length z pinch that implodes in 95 ns, and 57 MA to a pinch that implodes in 120 ns. The LTD-driven accelerator includes monolithic radial transformers and a MITL system similar to those described above, but does not include intermediate-store transmission lines, multimegavolt gas switches, or a laser trigger system. Instead, this accelerator is driven by 210 LTD modules that include a total of 1 10 6 capacitors and 5 10 5 200-kV electrically triggered gas switches. The LTD accelerator stores 182 MJ and produces a peak electrical power of 1000 TW. The accelerator delivers an effective peak current of 68 MA to a pinch that implodes in 95 ns, and 75 MA to a pinch that implodes in 120 ns. Conceptually straightforward upgrades to these designs would deliver even higher pinch currents and faster implosions.

Section: B Analytic Model Of An Ltd-based Acceleratormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Architecture of petawatt-classz-pinch accelerators

Stygar

Cuneo

Headley³

et al. 2007

215

128

“…Linear transformer drivers (LTDs) are a new pulsedpower architecture that may dramatically reduce the size and cost of high-voltage, high-current pulsed-power accelerators [1][2][3][4][5][6][7]. LTDs, however, place stringent demands on gas switches, requiring switches that can be charged to 200 kV DC, be triggered with a 1-jitter of 5-10 ns, be low inductance, have very low prefire and no-fire rates, and have lifetimes of at least several thousand shots when transferring $400 J of energy per shot.…”

Section: Introductionmentioning

confidence: 99%

New low inductance gas switches for linear transformer drivers

Woodworth

Stygar

Bennett

et al. 2010

We have developed two new gas switches that are designed to be used with linear transformer drivers. The switches, which can be DC charged to 200 kV and triggered with less than a 2-ns 1-jitter, have overall inductances ranging from 69 to 85 nH. When transferring 400 J of energy per shot, the switches have lifetimes in excess of 5000 shots. The two switches are insulated with 130-270 PSIA of air and are submerged in transformer oil during operation. These switches should allow development of linear transformer drivers that are more compact and have higher peak power.

“…The development of linear transformer driver (LTD) technology [1][2][3] for generating short, high current pulses represents a significant advance in the pursuit of the z-pinch-driven approach to inertial fusion energy (IFE) [4][5][6][7]. This design eliminates the need for large volumes of insulating oil and water which is required for present Marx bank driven generators, and a single compact unit can deliver significant current (> 1 MA).…”

Section: Introductionmentioning

confidence: 99%

250 kA compact linear transformer driver for wire arrayz-pinch loads

Bott

Haas

Madden

et al. 2011

We present the application of a short rise ($150 ns) 250 kA linear transformer driver (LTD) to wire array z-pinch loads for the first time. The generator is a modification of a previous driver in which a new conical power feed provides a low inductance coupling to wire loads. Performance of the new design using both short circuit and plasma loads is presented and discussed. The final design delivers $200 kA to a wire array load which is in good agreement with SCREAMER calculations using a simplified representative circuit. Example results demonstrate successful experiments using cylindrical, conical, and inverse wire arrays as well as previously published work on x-pinch loads.