CAPES Facilities

This is a brief description of some of the research facilities in the plasma engineering and fusion technology area. Other facilities (educational) will be added to this page later including MEDUSA, CYCLOPS and the CANCRUSHER PINCH machine.

[ SIRENS ] [ PIPE ] [ MAAT ] [ SIRENS-30 ] [ CPS-1 ] [ MAGTOR ]

SIRENS

Surface Interaction Research Experiment at North Carolina State University

The electrothermal plasma source facility SIRENS is a simulator for typical conditions of high heat flux deposition in plasma-driven launchers and fusion disruption. SIRENS produces low-temperature (1-3 eV) high-density (10E25-10E27 /m^3) plasma formed by the ablation of a liner inside a capillary discharge, with currents up to 100 kA. The maximum energy input to the plasma source is 100 kJ at a 10 kV charging potential. Material samples are shaped either in tube-form or flat discs. Tube-shaped samples are situated inside a stainless steel barrel connected to the source, and exposed to the plasma flow. Disc-shaped samples are exposed to the plasma at the source exit, where the plasma is incident normally or at an angle on the sample surface. The incident heat flux can be varied between 2 to 120 GW/m^2 over a 100 microsecond duration. The average plasma velocity is 10 - 12 km/s. The pulse power system is composed of modular capacitors with a pulse forming network that can extend the pulse length to 1 millisecond. The magnetic field is produced by a pulsed 2 kA current over 8 msec, which produces an average magnetic field of 16-20 Tesla at the barrel axis. Measurement of the heat flux is evaluated from the temperature increase of the wall, using fast response and infra red thermocouples. Measurement of the plasma temperature is evaluated from conductivity probes, optical emission spectroscopy and heat flux calorimetry. Diagnostics available on SIRENS include B-dot coils, internal and external Rogowiskii coils, capacitively-couples high voltage probes, absolute pressure transducers, infra red thermocouples, He-Ne lasers, opto-interrupters, break-wires array, and various fiber optic ports for optical emission spectroscopy. When used as a pellet injector, additional barrel extensions are installed to provide a longer acceleration path. The facility is also used as a simulator for disruption and abnormal events of tokamak fusion reactors. Additionally, it is used to characterize electrothermal plasma pre-injectors for railguns and other defense launching applications, and study of non ideal plasma behavior. Theory and modeling of plasma parameters, flow and acceleration mechanism include a number of developed computer codes. The ZEUS code, a 0-D, time dependent ablation- controlled arcs code, incorporates non-ideal plasma behavior in the electrothermal plasma sources section. The ODIN code, a 1-D, time dependent gas dynamics codes, describes plasma formation and behavior in the source and plasma flow and expansion through the barrel section. The POSEIDON code, a 1-D, time dependent plasma flow code incorporates acceleration of payloads inside the barrel. The MAGFIRE code (1-D, time dependent) incorporates the vapor and magnetic vapor shield effects, particle transport, ablation and mixing zones. The code also serves in other modeling jobs relevant to magnetic fusion reactors, which includes plasma-wall interactions and behavior of plasma-facing components, heat loading during abnormal events and current quench phase during plasma disruptions. The TURBFIRE code (2-D, time independent) describes the boundary layer flow system with a k-e turbulence model. This code incorporates magnetic field terms to allow modeling of electromagnetic launchers, and a combustion source term in the energy equation for modeling of electrothermal-chemical devices.

PIPE

Plasma Interaction with Propellant Experiment

The experimental facility PIPE is a device that injects electrothermal plasmas into solid or liquid propellants to study the interaction of such plasmas with propellants, and the mixing processes between plasma and chemical energies during combustion. The facility is powered by a pulse power energy delivery system that is composed of a 340 micro-Farad capacitor charged up to 10 kV to deliver up to 17 kJ of stored energy, with a discharge current of up to 100 kA. The source is formed from a 4 mm diameter capillary and thus operates on the basis of an ablation-controlled arc. A parallel transmission line is used to increase the pulse length to 400 microsecond, with a total system inductance of 800 nano-Henry. The combustion chamber is a 6 inch, 6-way stainless steel cube that contains two 3-D positioning pivot test stands for the propellant and material samples. Positioning is necessary so that the heat flux can be varied easily from high (close to the plasma) to low (farther away). Absolute pressure transducers are installed to measure the chamber pressure during the burn of the propellant. Discharge current and voltage are measured via a Rogowski coil and a compensated capacitively-coupled potential divider, respectively. Various diagnostics are arranged to allow for the measurement of the propellant's burn rate, pressure and stress distribution, heat flux calorimetry and plasma velocity. Fast response thermocouples and infrared detectors are used to measure the heat flux, and an infrared pyrometer monitors the surface and flame temperatures. Strain gauges measure the forces parallel and perpendicular to the direction of plasma flow, and fiber optics connected to an optical multichannel analyzer and photomultipliers measure the plasma parameters Rtemperature, density and composition". Theory and modeling of plasma parameters, flow, mixing and acceleration include a number of developed computer codes (click on SIRENS for information on codes). Modeling includes plasma flow and mixing at the plasma-propellant interface, plasma flame vapor shield at flame temperature, and combustion mechanisms.

MAAT

Materials and Armature Analysis Testbed

The MAAT Facility is an electromagnetic launcher with various barrels, ranging from short barrels of 12 inch in length to long 14-foot barrels. The facility is powered via a pulse power system composed of 6 high energy density capacitors and pulse forming network. A maximum of 100 kJ energy can be stored, then discharged via a spark-gap switch to deliver up to 100 kA of discharge current into the rails. The plasma armature may be generated via aluminum or copper fuses, or an electrothermal plasma pre-injector provides the initiation of the plasma armature. The barrels are equipped with equally-spaced absolute pressure transducers and B-dot probes. For example, the 12-inch barrel has 7 B-dot probes for rail current, 7 photodiode/fiber optic cable access for armature dynamics, 1 mid-barrel Piezoelectric pressure transducer for in-bore pressure and a mid-gun voltage probe. Additional diagnostics include a 7-element conductivity probes array for armature conductivity and plasma armature temperature, distributed strain gauges for stress distribution, 2 additional pressure transducers for velocity and drag forces, distributed thermocouples for heat flux measurements, optical emission spectroscopy via fiber optics to photomultipliers, and low energy x-ray attenuation and scattering measurements for plasma armature and boundary layer. Theory and modeling of plasma parameters, flow, mixing and acceleration include a number of developed computer codes (click on SIRENS for information on codes). Modeling includes plasma flow, eddy currents in rails, coupling and mutual inductance, armature-bore and armature-payload interface, and ablation, viscous and magnetic drag.

SIRENS-30

30 mm bore electrothermal-chemical launcher

The electrothermal-chemical facility SIRENS-30 is a high power combined version two devices, SIRENS and PIPE, which exhibits the generation of high density, high enthalpy flows for pulsed electrothermal launchers. SIRENS-30 operates at atmospheric conditions, where the electrothermal source generates the plasma by vaporization of metal fuses. The pulse power system stores 300 kJ of energy, which is delivered to the electrothermal source via an ignitron switch, with pulse length of up to 3 milliseconds. The plasma is injected into a combustion chamber (solid propellant bulk-loaded geometry) that is connected to 1 30 mm bore barrel. The facility is equipped with a blast and target tank which utilizes a hydraulic catcher system for in-door operation. The total length of the cartridge, combustion chamber and the barrel is 16 feet. The facility can also be used, without a combustion chamber) as a disruption simulator for future fusion reactors like ITER using large area armor tiles. heat fluence of up to 120 MJ/m^2, and greater, can be produced. Diagnostics include in-bore and ex-bore sensors for pressure, temperature, heat flux, velocity, acceleration, spectroscopy and burn rate measuring elements. Theory and modeling of plasma parameters, flow, mixing and acceleration include a number of developed computer codes (click on SIRENS and PIPE for information on codes). Modeling includes plasma flow and mixing at the plasma-propellant interface, plasma flame vapor shield at flame temperature, combustion mechanisms, and interior ballistics.

CPS-1

Coaxial Plasma Source 1

The CPS-l facility comprises a high pulse power supply and a magnetic coaxial plasma gun (MCG) mounted in a 16 inch diameter vacuum tank, with associated diagnostics and control elements. The high pulse power supply comprises a bank of 1.26 mF total capacitance with total energy storage of 63 kJ at 10 kV. The high pulse power supply is discharged into the MCG through an air spark gap switch, initiated by a fast rise (about 2 microsecond) high voltage pulse (12.5 kV) applied across the spark gap trigger pin and trigger electrode provided by a grounded cathode thyratron tube pulse generator. The gun is mounted on an end flange and inner flow is governed by the same flow equations while in the source, but is free to expand after being accelerated in the long gun channel. Since the flow is predicted to become magnetosonic at the muzzle in either case, the free expansion flow and nozzle flow have the same muzzle speed as they can no longer be influenced by the downstream conditions. The nozzle flow, however, shows additional velocity gain downstream over the muzzle velocity by nozzling in the diverging field outside the muzzle. Thus, the performance of MCG sources is analogous to that observed in hydrodynamic nozzles and free expansion flows. Additionally, the MCG source electrodes can be magnetically insulated to provide significant protection against plasma erosion and finely tuned tailoring of the flow stream. The MCG sources is used to provide studies on plasma thrusters for space applications, to inject plasmas (magnetic helicity injection) for Spheromak fusion reactors, to simulate disruption conditions in tokamak fusion reactors, and to provide simulation of relevant conditions in MHD astrophysical plasma jets.

MAGTOR

MAGnetically-controlled plasma TORch

The MAGTOR facility is a plasma torch for the incineration of various waste forms and treatment of low-level radioactive waste, that can provide a volume reduction of 100:1 or greater. The torch operates on a steady-state regime at a power level of 25 kW to provide about 80 MW/m^2 heat flux on the waste stream. The device is actively cooled, equipped with feed gas control, and the arc is magnetically-controlled. Theory and modeling include a 1-D, 2-region finite conducting boundary for MHD field-line distortion and stretching, including Hall effect.