STUDIES OF JOSHI EFFECT IN HYDROGEN

Production of the Joshi effect in H₂ under ozoniser excitation has been studied in respect of (I) gas pressure 120-200 mm.), (ii) temperature (15°-55°), (iii) frequency and intensity of incident light, (iv) appli­ed potential (0.67-2.13 kV), (v) frequency of A. C. supply, and (vi) ageing. Under favourable condi­tions, the system slims Joshi effect of as much as 50% current diminution under but visible light. As generalised by Joshi, the relative Joshi effect—% ∆\(i\), is (numerically) maximum at V_\(m\) the threshold potential and decreases thereafter. Gas pressure shows a limiting influence, Increase of (ii) and (v) decreases, while that of (iii) increases the effect. Moderate 'ageing' under the discharge due to a high potential, followed by allowing the system to stand over for limited periods, enhances the effect. Evidence has been adduced to show that the Joshi effect is not a consequence of selective absorption, nor due to destruction of metastable atoms under irradiation. These findings are in accord with Joshi's general theory of the phenomenon.