Absbnc+'l'hc 60 T Long-Pulse (60 'r LP) magnet systcm 1111s provided controlled power magnetic ficld pnlscs to experimentalists since August 3, 1398. This magnet system is installed as pmrt of the user facitity rosearch equipment at tho NationaI High Mngaetic Lnboretory (NIIMFL) Fulsctl Ficld Facility rt Los Alamos Nntionrl Laboratory. T h e 60 T LP magnct is the first of its kind in thc Unitcd Stntes nnd produces thc liighcst field in its class, routinely providing R 60 T piilscd field of 100 ms flat-top duration in B 32mm diametcr bore. In addition, numerous othcr controllcd pulsc shapcs at 60 T mnd lower fields I i w c been provided.Sincc the stnrt of commiasioning on Septembcr 17, 1997 the mrtgnet has hccn pulsed in excess of 800 timcs at vnrious field tevcls. More tlisn 600 magnet pulses ~R V C liecn provided to experimcnts slid almost 400 of these wcre at 60 T. Operating stntistics including coil systcm and inductance and resistance histories arc prcscntcd. Operating and maintcnancc cxperience ancl issiics are discussed as wcll RS rcalizriblc improvcmcnts and upgrrdes to thc Ihngnct.

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A technique for estimating and correcting nonuniform sampling distortions in magnetic resonance imagery is presented. The technique consists of first estimating the sampling grid distortion using a parametric model, and then estimating the uniformly sampled data by interpolation on the nonuniform grid. Parameterized models for two particular sampling grid distortion are presented. Maximum likelihood and maximum a posteriori estimators are developed for these distortions. Using computer simulated data, these estimators are shown to perform well.

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