Plasma contactor research, 1990

Emissive and Langmuir probes were used to measure plasma potential profiles, plasma densities, electron energy distributions, and plasma noise levels near a hollow cathode-based plasma contactor emitting electrons. The effects of electron emission current (100 to 1500 mA) and contactor flowrate (2 to 10 sccm (Xenon)) on these data are examined. Retarding potential analyzer (RPA) measurements showing that high energy ions generally stream from a contactor along with the electrons being emitted are also presented, and a mechanism by which this occurs is postulated. This mechanism, which involves a high rate of ionization induced between electrons and atoms flowing together from the hollow cathode orifice, results in a region of high positive space charge and high positive potential. Langmuir and RPA probe data suggests that both electrons and ions expand spherically from this potential hill region. In addition to experimental observations, a simple one-dimensional model which describes the electron emission process and predicts the phenomena just mentioned is presented and is shown to agree qualitatively with these observations. Experimental results of the first stage of bilateral cooperation with the Italian Institute of Interplanetary Space Physics (IFSI CNR) are presented. Sharp, well-defined double layers were observed downstream of a contactor collecting electrons from an ambient plasma created in the IFSI Facility. The voltage drop across these double layers was observed to increase with the current drawn from the ambient plasma. This observation, which was not as clear in previous IFSI tests conducted at higher neutral pressures, is in agreement with previous experimental observations made at both Colorado State University and NASA Lewis Research Center. Greater double layer voltage drops, multiple double layers, and higher noise levels in the region near the double layers were also observed when a magnetic field was imposed and oriented perpendicular to the line joining the contactor and simulator

Space plasma contractor research, 1988

Results of experiments conducted on hollow cathode-based plasma contractors are reported. Specific tests in which attempts were made to vary plasma conditions in the simulated ionospheric plasma are described. Experimental results showing the effects of contractor flowrate and ion collecting surface size on contactor performance and contactor plasma plume geometry are presented. In addition to this work, one-dimensional solutions to spherical and cylindircal space-charge limited double-sheath problems are developed. A technique is proposed that can be used to apply these solutions to the problem of current flow through elongated double-sheaths that separate two cold plasmas. Two conference papers which describe the essential features of the plasma contacting process and present data that should facilitate calibration of comprehensive numerical models of the plasma contacting process are also included

The Everyday at Grassroots level: poverty, protest and social change in post-apartheid South Africa

This paper was originally presented to the International Workshop “Development and Social Movements in the South”, organised by “The Africa, Asia and Latin America Scholarly Collaborative Program”, supported by the Swedish International Development Cooperation Agency and held in Rio de Janeiro, april 2008.This paper posits that social change derives from how the everyday is encountered, analyzed and experienced at the grassroots level. Drawing extensively from the seminal work of Henri Lefebvre, the paper argues that for ordinary people in post-apartheid South Africa, the everyday is often an instantiation of multiple contradictions, tensions, conflicts and struggles as the promises of a “better life for all”, the mantra of the Mbeki government, would appear to remain largely rhetorical as evidenced by the increasing levels of homelessness and unemployment since the creation of the democratic State in 1994. The failure to substantively improve the everyday reality experienced by the poor, homeless and unemployed, has given rise throughout the country, especially from 2004 to 2009, to massive protests by communities against local authorities (municipalities). The paper concludes by considering the question whether or not this type of community discontent could serve to transform the everyday into a more equitable and democratic dispensation at the grassroots level

Gerwel taught us that theory without application is useless

This tribute to Prof Gerwel has been triggered by a picture on p 2 of the Cape Times, 29 Nov 2012, of a group of students, he addressed in 1977 [not 1973] as I was reading for my Honours degree in Geography. As students we admired him deeply for his seemingly effortless ability to apply profound theoretical insights to the existential reality of apartheid and its nefarious effects on society as a whole. He usually addressed us during lunch-hour, in the Science Block. Every student leader of the different student organizations on campus was usually there, even the deeply- spiritual students, like myself [I headed the Anglican Student Society of Southern Africa [ANSOC/ASF] in the Western Cape, at UWC, US and UCT

South Africa: Urban transformation

This paper discusses transformation as a multi-dimensional concept to effect social change in South African society in the post-apartheid era. The policy implications of such a variegated understanding of social change are examined with special reference to planning principles such as holism, capacity building, self-reliance, community integration, participatory democracy and so forth. It is argued that transformation is a multi-dimensional process, and whilst on the basis of provisional evidence there appears to be nascent forms of socio-spatial change, structurally, such apparent change is shot through by a number of contradictions, tensions and potential conflicts.DHE

The politics of social change and the transition to democratic governance: Community participation in post-apartheid South Africa

Community participation, i.e. the direct involvement/engagement of ordinary people in the affairs of planning, governance and overall development programs at the local or grassroots level, has become an integral part of democratic practice in recent years (cfJayal, 2001). In the case of post-apartheid South Africa, community participation has literally become synonymous with legitimate governance. In this regard, for example, the Municipal Structures Act, Chapter 4, subsections (g) and (h) state respectively that the 'executive mayor [should] annually report on the involvement of community organisations in the affairs of the municipality' and 'ensure that due regard is given to public views and report on the effect of consultation on the decisions of council' (RSA, 1998c). Yet it would seem that most community participation exercises in post-apartheid South Africa are largely spectator politics, where ordinary people have mostly become endorsees of pre-designed planning programs, often the objects of administrative manipulation and a miracle of reconciliation in the international arena of consensus politics, while state functionaries of both the pre- and post-apartheid eras ensconce themselves as bureaucratic experts summonsed to 'ensure a better life for all'. Consequently, the process, visions and missions of a more equitable society operate merely as promissory notes issued every five years during election campaigns. In this course of endless rhetoric and multiple platitudes, the very concept of community participation has been largely reduced to a cumbersome ritual—a necessary appendix required by the various laws and policies operating at the local government level