Scaling of the rise time of drive current on the development of magneto-Rayleigh-Taylor instabilities for single-shell Z-pinch

We investigate the implosion of a dense τ-pinch plasma driven by an annular finite-thickness gas-puff Z-pinch. The imploding Z-pinch traps an axial magnetic field Bz, compressing it to large values in an extremely short time. The temporal variation of Bz then induces an azimuthal τ current on the surface of a fibre placed on the axis, with a rise time an order of magnitude shorter than the rise time of the Z-pinch current. Our numerical results demonstrate that, for a thick gas-puff layer, maximum compression occurs before the current peaks.We also find that at peak compression, fuel densities of the order of 1025 cm-3 and temperatures above 10 keV can be achieved on a time scale of the order of 0.1 ns. Thus a Lawson parameter nτ ≈ 1014 s cm-3 for a DT fibre becomes achievable. The snowplough effect in the Z-pinch exercises a stabilization effect on the growth of sausage and Rayleigh—Taylor instabilities. In the limit of a very thin gas-puff layer, previous results are fully recovered.

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Source of megaampere current with the rise time ∼100 ns on the basis of explosive magnetic generator

Доклады Академии наук ◽

10.31857/s0869-56524894355-357 ◽

2019 ◽

Vol 489 (4) ◽

pp. 355-357

Author(s):

A. A. Bazanov ◽

E. I. Bochkov ◽

S. G. Garanin ◽

P. V. Duday ◽

A. A. Zimenkov ◽

...

Keyword(s):

Current Pulse ◽

Rise Time ◽

Current Source ◽

Two Stage ◽

Explosive Magnetic Generator ◽

Ignition Threshold ◽

Z Pinch ◽

Thermonuclear Ignition ◽

Magnetic Generator

To achieve a thermonuclear ignition threshold in the scheme of indirect irradiation of Z‑pinch by X‑radiation, it is necessary to implode the liner by the current with the amplitude 65 МА for the time 100 ns. The currents with such parameters can be achieved with the use of super-power disk explosive magnetic generators and a two-stage current pulse sharpening system based on foil electrically exploded current opening switches in a form of a serpentine. The implementation of the explosive current source with a rise time of 100 ns is advisable to be carried out in stages by increasing the magnitude of current. The results of the first-stage experiments, in which the current with the amplitude of 5 MA was produced on the basis of the helical explosive magnetic generator in the load of 10 nH for the time of 110 ns, are presented.

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Implosion characteristics of gas-puff Z-pinch with a single-shell nozzle

Acta Physica Sinica ◽

10.7498/aps.58.7067 ◽

2009 ◽

Vol 58 (10) ◽

pp. 7067

Author(s):

Ren Xiao-Dong ◽

Huang Xian-Bin ◽

Zhou Shao-Tong ◽

Zhang Si-Qun ◽

Li Jing ◽

...

Keyword(s):

Z Pinch ◽

Single Shell

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Effect of tailored density profiles on the stability of imploding z-pinches at microsecond rise time megaampere currents

Plasma Physics and Controlled Fusion ◽

10.1088/1361-6587/ac35a5 ◽

2021 ◽

Author(s):

Rustam K Cherdizov ◽

R Baksht ◽

Vladimir A Kokshenev ◽

Vladimir Oreshkin ◽

Alexander Rousskikh ◽

...

Keyword(s):

Rise Time ◽

Initial Density ◽

Plasma Jet ◽

Vacuum Arc ◽

Radial Density ◽

Radiation Yield ◽

High Current Electronics ◽

Density Profiles ◽

Z Pinch ◽

A Current

Abstract To study the effect of the radial density profile of the material of a metal-plasma Z-pinch load on the development of magneto-Rayleigh-Taylor (MRT) instabilities, experiments have been performed at the Institute of High Current Electronics with the GIT-12 generator produced microsecond rise time megaampere currents. The load was an aluminum plasma jet with an outer plasma shell. This configuration provides the formation of a uniform current sheath in a Z-pinch load upon application of a high voltage pulse. It was successfully used in experiments with hybrid deuterium gas-puffs [Klir et al. 2020 New J. Phys. 22 103036]. The initial density profiles of the Z-pinch loads were estimated from the pinch current and voltage waveforms using the zero-dimensional "snowplow" model, and they were verified by simulating the expansion of the plasma jet formed by a vacuum arc using a two-dimensional quasi-neutral hybrid model [Shmelev et al. 2020 Phys. Plasmas 27 092708]. Two Z-pinch load configurations were used in the experiments. The first configuration provided tailored load density profiles, which could be described as ρ(r) ≈ 1/r^s for s > 2. In this case, MRT instabilities were suppressed and thus a K-shell radiation yield of 11 kJ/cm and a peak power of 0.67 TW/cm could be attained at a current of about 3 MA. For the second configuration, the radial density profiles were intentionally changed using a reflector. This led to the appearance of a notch in the density profiles at radii of 1–3 cm from the pinch axis and to magnetohydrodynamic instabilities at the final implosion stage. As a result, the K-shell radiation yield more than halved and the power decreased to 0.15 TW/cm at a current of about 3.5 MA.

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Scaling of magnetized inertial fusion with drive current rise-time

Physics of Plasmas ◽

10.1063/1.5040116 ◽

2018 ◽

Vol 25 (8) ◽

pp. 082707 ◽

Cited By ~ 6

Author(s):

S. A. Slutz

Keyword(s):

Rise Time ◽

Inertial Fusion ◽

Drive Current ◽

Current Rise Time ◽

Current Rise

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THEORETICAL MODEL FOR A FINITE-THICKNESS GAS-PUFF Z-Θ PINCH

Modern Physics Letters B ◽

10.1142/s0217984993001685 ◽

1993 ◽

Vol 07 (26) ◽

pp. 1655-1660 ◽

Cited By ~ 2

Author(s):

ARSHAD M. MIRZA ◽

M. IQBAL ◽

N.A.D. KHATTAK ◽

G. MURTAZA

Keyword(s):

Magnetic Field ◽

Theoretical Model ◽

Time Scale ◽

Rise Time ◽

Finite Thickness ◽

Current Sheath ◽

Constant Mass ◽

Pinch Current ◽

Z Pinch ◽

Ultrahigh Magnetic Field

A dynamic model for a finite-thickness gas-puff Z-θ pinch is proposed. The snowplow effect is incorporated to describe the dynamics of an imploding annular plasma shell of finite thickness. Our numerical results demonstrate that for a thick gas-puff layer, fast compression occurs which produces an ultrahigh magnetic field on a time scale much less than the rise time of the Z-pinch current. For a very thin puff layer, however, the current sheath moves like a constant mass layer as described by Rahman et al.

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Desain dan Komparasi Kontrol Kecepatan Motor DC

Jurnal ECOTIPE ◽

10.33019/jurnalecotipe.v7i2.1886 ◽

2020 ◽

Vol 7 (2) ◽

pp. 127-134

Author(s):

Safah Tasya Aprilyani ◽

Irianto Irianto ◽

Epyk Sunarno

Keyword(s):

Steady State ◽

Rise Time ◽

Settling Time ◽

Proportional Integral

Penggunaan kontrol sangat diperlukan dalam pengaturan kecepatan motor DC. Dalam pengaturan kecepatan motor DC, salah satu jenis kontrol yang digunakan adalah kontrol Proportional Integral (PI). Untuk 4 jenis metode pada kontrol PI yang digunakan adalah metode Ziegler Nichole, Chien Servo 1, Chien Regulator 1 dan perhitungan secara analitik yang telah diperoleh dari data yang sudah ada. Namun kontrol dengan PI 4 metode yang digunakan sebagai pembanding memiliki waktu respon kecepatan saat stabil cenderung lambat baik dari nilai settling time, rise time dan steady state. Maka dari itu dilakukan komparasi antara 4 metode kontrol PI dengan penggunaan kontrol fuzzy. Dalam membandingkan antara 4 metode kontrol PI dan kontrol fuzzy terdapat beberapa parameter sebagai perbandingan yaitu maximum overshoot, steady state, rise time dan settling time. Hasil dari perbandingan tersebut adalah kontrol fuzzy dapat menghasilkan performa lebih baik jika dibandingkan dengan 4 metode pada kontrol PI. Kontrol fuzzy memiliki nilai rise time sebesar 0,015 detik, nilai settling time sebesar 0,025 detik dengan kecepatan sebesar 2900 rpm serta error steady state sebesar 3,33% tanpa adanya overshoot dan osilasi.

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STABILISASI TEGANGAN KELUARAN BUCK CONVERTER DENGAN METODE FUZZY LOGIC CONTROLLER

JURNAL ELTEK ◽

10.33795/eltek.v16i2.104 ◽

2018 ◽

Vol 16 (2) ◽

pp. 125

Author(s):

Oktriza Melfazen

Keyword(s):

Fuzzy Logic ◽

Steady State ◽

Rise Time ◽

Fuzzy Logic Controller ◽

Buck Converter ◽

Settling Time

Buck converter idealnya mempunyai keluaran yang stabil, pemanfaatandaya rendah, mudah untuk diatur, antarmuka yang mudah dengan pirantiyang lain, ketahanan yang lebih tinggi terhadap perubahan kondisi alam.Beberapa teknik dikembangkan untuk memenuhi parameter buckconverter. Solusi paling logis untuk digunakan pada sistem ini adalahmetode kontrol digital.Penelitian ini menelaah uji performansi terhadap stabilitas tegangankeluaran buck converter yang dikontrol dengan Logika Fuzzy metodeMamdani. Rangkaian sistem terdiri dari sumber tegangan DC variable,sensor tegangan dan Buck Converter dengan beban resistif sebagaimasukan, mikrokontroler ATMega 8535 sebagai subsistem kontroldengan metode logika fuzzy dan LCD sebagai penampil keluaran.Dengan fungsi keanggotaan error, delta error dan keanggotaan keluaranmasing-masing sebanyak 5 bagian serta metode defuzzifikasi center ofgrafity (COG), didapat hasil rerata error 0,29% pada variable masukan18V–20V dan setpoint keluaran 15V, rise time (tr) = 0,14s ; settling time(ts) = 3,4s ; maximum over shoot (%OS) = 2,6 dan error steady state(ess) = 0,3.

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