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Experimental evidence is reported for the presence of oppositely rotating plasma cells during spheromak formation. The toroidal rotations are caused by jxB forces and cause a twisting of axial (i.e., poloidal) magnetic field into the toroidal direction. Calculations of the magnetic heiicity input are consistent with measured heiicity values. This method of flux conversion can be interpreted as a mechanical source of magnetic heiicity injection possibly useful for magnetic confinement of plasmas.PACS numbers: 52.55. He, 95.30.Qd, 96.60.Pb It has long been recognized that flow velocity can play an important role in the appearance of magnetic fields in conducting fluids J Originally, this realization came from a study of MHD wave motion in magnetized conducting fluids. Astrophysicists have also investigated the twisting and stretching of magnetic fields in plasmas in order to explain the conversion of one component of field to another, the amplification of fields, and the generation of fields. ^' Recently, there has been consideration of the twisting of magnetized solar corona loops by footpoint motion in an eff'ort to understand the heating of coronal loops/-^ In the context of laboratory spheromak formation, velocity fields can aff'ect magnetic heiicity injection,^ require the need for consideration of cross heiicity,^ and act as a source or sink of energy. These considerations may be important in magnetic relaxation to the minimum-energy configuration.^'^ The essence of magnetic relaxation and magnetic heiicity injection is the transfer of magnetic flux from one component to another. In all experiments to date, including this one, magnetic heiicity injection comes about either by voltages applied to electrodes or by externally applied, time-changing magnetic fields. In principle, this flux transfer can come about by mechanical twisting of flux tubes followed by reconnection.In this paper, we report our observation of counterrotating plasma cells during spheromak formation. The source of rotation in this experiment is the jxB force density resulting from electrode derived plasma current and externally applied magnetic fields. The velocity gradients have been shown to provide a means of flux conversion and can be thought of as the initiating action in a mechanical source of heiicity injection. Extension of these ideas leads us to the conclusion that it may be possible to form spheromaks, or inject heiicity, by mechanically transferring momentum from beams, for example. Estimates are made of the mechanical injection rate associated with rotation, which is independent of the source of the rotation, and compared to the more standard electrostatic heiicity injection rate.We have reported '^ the observation of the shift of carbon impurity spectral lines emitted from a plasma during spheromak formation in the PS-3 and PS-3.5 devices. In these experiments, the spheromak is formed by a combination of inductive and electrode discharges. ^ ^ The experimental geometry is a cylinder with a ring of electrodes at each end and...

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Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Approved for public release; distribution is unlimited. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S ACRONYM(S) 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S REPORT NUMBER(S)The Chemistry Division of the Naval Research Laboratory has developed the Multi-sensor Towed Array Detection System (MTADS) for the detection and classification of buried unexploded ordnance. In order to increase the discrimination ability of the system, we have developed advanced analysis algorithms for the Electromagnetic Induction (EMI) sensor data. In order to critically test the performance of these algorithms, we performed a magnetometer and two EMI surveys of a seeded, 10-acre site on the Impact Area of the Badlands Bombing Range, SD. We quantitatively compare the predictions from a baseline MTADS magnetometry analysis, an advanced EMI analysis, and a probabilistic neural net approach developed in a related SERDP program against actual remediation results. In addition, we discuss the performance of the EMI system in both a low-and high-SNR environment.