A high‐efficiency solution‐processed inverted perovskite solar cell with poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)benzidine] (poly‐TPD) as the hole transport layer is demonstrated. The perovskite forms large crystallites on poly‐TPD, yielding devices with an average power conversion efficiency of 13.8% and a maximum of 15.3%.

The letter reports the first use of laser ablation of trace impurities into a reversed field pinch (RFP) similar to that used in tokamaks, but selecting different impurity elements appropriate to the confinement times of present RFPs. The ionization rates from helium-like carbon and boron are sufficiently slow to allow measurements of particle confinement times from line intensity decay rates of the near UV transitions. A zero-dimensional treatment, incorporating impurity ionization and confinement, is used to interpret the temporal behaviour of the line intensity. The results obtained yield typical particle confinement times of about 1 ms.

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Since 1964, when this machine became operational, a substantial amount of the atomic collision studies at the Institute have been performed at this facility. The studies have included channeling and energyloss measurements, beam-foil experiments, and investigations of single and multiple atomic collisions.

A 9 GHz free-space microwave interferometer was used to measure the electron density decline over the range 1011-1010 cm−3 in the afterglow of a pulsed argon discharge in a 12·7 cm diameter cylindrical tube (characteristic diffusion length Λ=2·46 cm). In the range 0·14-0·61 torr the results are interpreted in terms of the ion conversion mechanism Ar++2Ar->Ar2++Ar. The conversion frequency, found to be 376p02 s−1 (p0 being the pressure reduced to 273°K), is compared with the available theoretical values. Owing to the high electron density and large-diameter discharge tube the present method is more suitable for the measurement of this parameter in argon than were previous microwave studies.

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