Dual wavelength imaging of a scrape-off layer in an advanced beam-driven field-reversed configuration

August 2016 | D. Osin | Review of Scientific Instruments | Paper

A dual wavelength imaging system has been developed and installed on C-2U to capture 2D images of a He jet in the Scrape-O↵ Layer (SOL) of an advanced beam-driven Field-Reversed Configuration (FRC) plasma. The system was designed to optically split two identical images and pass them through 1 nm FWHM filters.

Enhanced magnetic field probe array for improved excluded flux calculations on the C-2U advanced beam-driven field-reversed configuration plasma experiment

August 2016 | T. Roche | Review of Scientific Instruments | Paper

External flux conserving coils were installed onto the exterior of the C-2U confinement vessel to increase the flux confinement time of the system. The 0.5 in. stainless steel vessel wall has a skin time of ⇠5 ms. The addition of the external copper coils e↵ectively increases this time to ⇠7 ms.

Characterization of compact-toroid injection during formation, translation, and field-penetration

July 2016 | T. Matsumoto | Review of Scientific Instruments | Paper

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam- driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U.

A mass resolved, high resolution neutral particle analyzer for C-2U

July 2016 | Ryan Clary | Review of Scientific Instruments | Paper

C-2U is a high-confinement, advanced beam driven field-reversed configuration plasma experiment which sustains the configuration for >5 ms, in excess of typical MHD and fast particle instability times, as well as fast particle slowing down times.

Innovative high-gain optically pumped far-infrared laser

July 2016 | B. Deng | Applied Optics | Paper

A new optically pumped far-infrared (FIR) laser with separate pump beam reflector and FIR output coupler has been developed. The new design greatly simplifies the tuning of the laser and enables the optimization of the pump beam absorption without affecting the laser alignment.

Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device

May 2016 | T. Matsumoto | Review of Scientific Instruments | Paper

A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field- reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field.

Transport studies in high-performance field reversed configuration plasmas

May 2016 | S. Gupta | Physics of Plasmas | Paper

A significant improvement of field reversed configuration (FRC) lifetime and plasma confinement times in the C-2 plasma, called High Performance FRC regime, has been observed with neutral beam injection (NBI), improved edge stability, and better wall conditioning.

Control of ion gyroscale fluctuations via electrostatic biasing and sheared E×B flow in the C-2 field reversed configuration

March 2016 | L. Schmitz | AIP Conference Proceedings | Paper

Control of radial particle and thermal transport is instrumental for achieving and sustaining well-confined high-β plasma in a Field-Reversed Configuration (FRC). Radial profiles of low frequency ion gyro-scale density fluctuations (0.5 ≤ kρs ≤ 40), consistent with drift- or drift-interchange modes, have been measured in the scrape-off layer (SOL) and core of the C-2 Field-Reversed Configuration (FRC), together with the toroidal ExB velocity.

Robustness of waves with a high phase velocity

March 2016 | T. Tajima | AIP Conference Proceedings | Paper

Norman Rostoker pioneered research of (1) plasma-driven accelerators and (2) beam-driven fusion reactors. The collective acceleration, coined by Veksler, advocates to drive above-ionization plasma waves by an electron beam to accelerate ions. The research on this, among others, by the Rostoker group incubated the idea that eventually led to the birth of the laser wakefield acceleration (LWFA), by which a large and robust accelerating collective fields may be generated in plasma in which plasma remains robust and undisrupted.

End loss analyzer system for measurements of plasma flux at the C-2U divertor electrode

March 2016 | M. E. Griswold | AIP Conference Proceedings | Paper

An end loss analyzer system was developed to study thermal transport on the open field lines that surround the advanced beam-driven field-reversed configuration (FRC) core of the C-2U experiment. The system is mounted directly to the divertor electrode and consists of gridded retarding-potential analyzers that measure ion current density and ion energy as well as pyroelectric crystal bolometers that measure the total power flux.