The transient internal probe: A novel method for measuring internal magnetic field profilesa)

A simple and high performance sabot separation technique which is useful even in about 10-m-long supersonic ballistic ranges has been developed. The normal in-flight sabot separation distance is vastly reduced by adding an addition tube with no diaphragm that may cause damage to the projectile. The launch tube of the ballistic range is subdivided to the acceleration, ventilation, and sabot separation sections. In the ventilation section, both the precursor shock wave driven by the sabot when coasting through the acceleration section and the driver gas is vented out to the dump chamber. In the sabot separation section, only the sabot experiences a great dragging pressure imbalance whereas the drag to the projectile is kept negligible. Initially, the whole system except for the driver gas chamber is connected without any diaphragm; the range operation is not accompanied by any high-speed impact among the sabot, diaphragm, and other related solid parts. The experimental environment can be kept clean. The influence of the muzzle blast is eliminated within a reasonably short distance from the muzzle because it delays owing to the ventilation section. Calibration experiments and the demonstration of flow visualization and boom measurement of supersonic flight were conducted using a 25 mm bore, Mach-2 ballistic range.

Section: Introductionmentioning

confidence: 99%

Impactless, in-tube sabot separation technique useful for modest-sized supersonic ballistic ranges

Sasoh

Oshiba

2006

Magnetic field measurements using the transient internal probe (TIP)

Galambos

Bohnet

Jarboe

et al. 1996

The transient internal probe (TIP) is a novel diagnostic technique for measuring magnetic fields in hot plasmas. The concept involves shooting a diamond clad magneto-optic probe through the plasma at high velocity allowing measurement of the local magnetic field before ablation occurs. Magnetic field measurements are obtained by illuminating the probe with an argon laser and measuring the amount of Faraday rotation in the reflected light. The diagnostic was tested by measuring a permanent magnetic field inside a vacuum chamber with a probe traveling at 2 km/s using an unclad probe. The purpose of this experiment was to demonstrate the capability of the TIP diagnostic and to verify compatibility with plasma vacuum requirements. Magnetic field resolutions of 20 G and 1 cm spatial resolution were achieved. The response time of the detection system is 10 MHz. Introduction of a helium muzzle gas into the plasma chamber was limited to less than 0.4 Torr ℓ.

Plasma diagnostics for the sustained spheromak physics experiment

McLean

Ahmed

Buchenauer

et al. 2001

In this article we present an overview of the plasma diagnostics operating or planned for the sustained spheromak physics experiment device now operating at Lawrence Livermore National Laboratory. A set of 46 wall-mounted magnetic probes provide the essential data necessary for magnetic reconstruction of the Taylor relaxed state. Rogowski coils measure currents induced in the flux conserver. A CO2 laser interferometer is used to measure electron line density. Spectroscopic measurements include an absolutely-calibrated spectrometer recording extended domain spectrometer for obtaining time-integrated visible ultraviolet spectra and two time-resolved vacuum monochrometers for studying the time evolution of two separate emission lines. Another time-integrated spectrometer records spectra in the visible range. Filtered silicon photodiode bolometers provide total power measurements, and a 16 channel photodiode spatial array gives radial emission profiles. Two-dimensional imaging of the plasma and helicity injector is provided by gated television cameras and associated image-processing software. An array of fiber-coupled photodetectors with H alpha filters view across the midplane and in the injector region to measure neutral hydrogen concentrations. Several novel diagnostics are being fielded including a transient internal probe (TIP) and an ultrashort-pulse reflectometer (USPR) microwave reflectometer. The TIP probe fires a very high velocity optical bullet through the plasma and will provide fairly nonpertabative internal magnetic field and current measurements to compare with an equilibrium code model fitted to wall-mounted probes. The USPR is being designed to study edge density and turbulent fluctuations. A multipoint Thomson scattering system is currently being installed to give radial temperature and density profiles.