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Contains reports on eight research projects split into two sections., National Science Foundation (Grant GK-1165)

Contains reports on ten research projects., U. S. Air Force under Contract AF 19(628)-500, U. S. Atomic Energy Commission under Contract AT(30-1)-3211, U. S. Atomic Energy Commission under Contract AT(30-1)-3221, National Science Foundation (Grant G-24073), Lincoln Laboratory, Purchase Order DDL BB-107

Contains reports on eleven research projects split into three section., U. S. Atomic Energy Commission (Contract AT(30-1)-3980)

Contains reports on five research projects split into three sections., National Science Foundation (Grant GK-10472), Joint Services Electronics Programs (U.S. Army, U.S. Navy, and U.S. Air Force)under Contract DA 28-043-AMC-02536(E)

Contains research objectives and reports on three research projects., National Science Foundation (Grant GK-2581), Joint Services Electronics Program under Contract DA 28-043-AMC-02536(E)

Contains research objectives and reports on four research projects., U. S. Atomic Energy Commission (Contract AT(30-1)-3980), U. S. Atomic Energy Commission (GK-2581)

Contains reports on twelve research projects split into three sections., National Science Foundation (Grant GK-57), National Science Foundation (Grant GK-1165)

Contains reports on three research projects., National Science Foundation (Grant GK-10472), Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)

Contains reports on two research projects., National Science Foundation (Grant GK-2581)

Contains reports on three research projects., National Science Foundation (Grant GK-10472)

Contains research objectives and reports on three research projects., National Science Foundation (Grant GK-1165), National Science Foundation (Grant GK-57)

Contains research objectives and reports on six research objectives., National Science Foundation (Grant G-24073), Lincoln Laboratory, Purchase Order DDL BB-107, U. S. Air Force under Contract AF 19(628)-500

Contains reports on four research projects., United States Army, United States Navy, United States Air Force (Contract AF19(604)-7400), Lincoln Laboratory (Purchase Order DDL BB-107), National Science Foundation (Grant G-24073)

Contains reports on nine research projects., National Science Foundation (Grant G-24073), United States Navy, United States Navy, Office of Naval Research (Contract Nonr-1841(78)), United States Air Force (Contract AF19(604)-7400), Lincoln Laboratory (Purchase Order DDL B-00368), United States Army

Contains research objectives and reports on two research projects., U. S. Air Force under Air Force Contract AF19(604)-5200, U. S. Navy (Office of Naval Research) under Contract Nonr-1841(49), U. S. Navy, U. S. Army, Lincoln Laboratory, Purchase Order DDL B-00306

Contains a report on a research project., United States Army, United States Navy, Office of Naval Research (Contract Nonr-1841(49)), Lincoln Laboratory (Purchase Order DDL B-00368), United States Air Force (Contract AF19(604)-7400), United States Navy

Contains research objectives and reports on two research projects., U. S. Navy (Office of Naval Research) under Contract Nonr-1841(49), U. S. Air Force under Air Force Contract AF19(604)-7400., U. S. Navy, U. S. Army, Lincoln Laboratory, Purchase Order DDL B-00306

A decade ago, New American Schools (NAS) launched an ambitious effort for whole-school reform to address the perceived lagging achievement of American students and the lackluster school reform attempts that produced so little meaningful change. As a private non-profit organization, NAS set out to help schools and districts significantly raise the achievement of large numbers of students by offering whole-school designs and design-based assistance during the implementation process. NAS is currently in the scale-up phase of its effort and its designs are being widely diffused to schools across the nation. The purpose of this study is to examine the conditions of NAS classrooms compared with non-NAS classrooms and to study the relationships between classroom conditions and student achievement in a high-poverty district in San Antonio, Texas. The focus is on the conditions in the district, schools, and classrooms that promote or inhibit design implementation and changes in teaching and learning. Specifically, this study addresses the following questions: * Do the NAS designs extend beyond changes in school organization and governance and permeate classrooms? Do NAS teachers and students interact with each other and subject materials in ways that reflect the innovative curricular and instructional approaches of the design teams? * What factors at the district, school, and classroom level are related to implementation of designs, changes in classroom instruction, and student achievement?

A decade ago, New American Schools (NAS) launched an ambitious effort for whole-school reform to address the perceived lagging achievement of American students and the lackluster school reform attempts that produced so little meaningful change. As a private non-profit organization, NAS set out to help schools and districts significantly raise the achievement of large numbers of students by offering whole- school designs and design-based assistance during the implementation process. NAS is currently in the scale-up phase of its effort Its designs are being widely diffused in partnering jurisdictions across the nation. The purpose of this report is to examine the conditions of NAS classrooms compared with non-N AS classrooms and to study the relationships between classroom conditions and student achievement The focus is on the conditions in the district, schools, and classrooms that promote or inhibit design implementation and changes in teaching and learning.

The experimental program uses the 4 MeV, 100 ampere, 0.3 microsec pulse width, beam from the Astron accelerator facility to study the interaction of an intense relativistic electron beam with a gas column, usually at a pressure of a few mm Hg. The beam promptly ionizes the gas, generating a plasma column in and around the beam. In this environment measurements were made pertinent to two beam driven instabilities, namely the streaming instability and the hose instability., Supported by the Advanced Research Projects Agency, Arlington, Va.

The objective of this study is to determine the feasibility of a microwave time-delay device employing an ion beam. The inherently low drift velocity of ion suggests the possibility of a broadband device with a long variable delay. The program is divided into three major problem areas: (1) ion sources, (2) beam transmission and (3) RF experiments. Thermionic emitters of alkali ions are used as the source of ions. A novel technique has been developed to fabricate 'impregnated' ion emitters. The ion current density (Li+ and K+) of several mA/sq cm has been obtained. At low frequencies the delay of the AC modulation on the ion beam was measured. Variable time delays greater than 1 microsec have been measured. The problem of RF signal coupling to the ion beam has been investigated at microwave frequencies. Novel methods of the RF coupling by transferring modulation from an electron beam to an ion beam are discussed. (Author)

Experimental studies of the ion-beam delay line at 500 MHz are described. The emphasis of the present study is on the technique of ion-beam modulation by the transfer of modulation from an electron beam to the ion beam. The theory of modulation transfer mechanism by a reflecting electron beam is presented, and the experiment to observe the effect is described. Based on results of these investigations, it was concluded that the most promising method of ion-beam modulation is the classical technique of gap modulation. An experimental device was designed and constructed to demonstrate the feasibility of the ion-beam delay line at 500 MHz. (Author)

Experimental studies of the transit-time delay and the low-frequency modulation of the ion-beam are described. The variable delay in the transit time of up to 1 microsec has been obtained through a drift tube 6 cm long. The delay of the low-frequency RF signal (1-200 kc) of the same order has been observed. The method of coupling RF signals into and out of ion beams by using electron beams as an intermediary has been studied experimentally. The output coupling is achieved through the secondary electrons. The input coupling may be also achieved by the transfer of the RF modulation from an electron beam to the ion beam. Experiments at low frequencies (1 kc) have shown that the modulation transfer does indeed occur as a result of the space-charge modulation in the potential maximum by secondary electrons. (Author)

A theoretical analysis of the beam energy spread induced by transverse-wave interactions is presented. The theory includes effects of finite beam size, space charges and rotation of the beam. A nonlinear theory is also developed to show a power saturation effect in synchronous-wave traveling-wave tubes due to velocity slipping caused by extended traveling-wave interactions. Results of these two theoretical studies point out important practical limitations on the output power and the efficiency of transverse-wave devices. An experimental vehicle designed as a diagnostic tool to investigate various effects theoretically predicted is described. (Author), See also Triannual rept. no. 2, AD-689 472.

Under certain circumstances the problem of the stability of low density crossed-field electron beams is precisely analogous to the problem of the stability of incompressible inviscid shear flows. The electron density, the drift velocity, and the potential correspond to the fluid vorticity, velocity, and the stream function respectively. The analogy is valid only for waves propagating in the direction of the unperturbed velocity. Neutrally stable normal modes of oscillation that are found when certain suitable step-function unperturbed electron density (vorticity) profiles are assumed seem to disappear when small gradients are present. In the context of a Laplace transform solution of the initial value problem, the vanishing normal modes can be found by analytic continuation of the solution onto another sheet of the cut complex omega-plane. The 'recovered' modes are found to be damped by a fluid-wave resonant interaction which closely resembles the Landau damping of plasma oscillations in warm plasmas by particle-wave resonance. An interesting feature of the neutral waves is that they have a negative energy and so are destabilized by the removal of energy from the system (for example, by slightly dissipative walls). The sign and magnitude of the Landau damping term is evaluated for a simple case and compared (for the electronic case) with the growth provoked by slightly lossy walls. (Author), Sponsored in part by National Aeronautics and Space Administration, Huntsville, Ala. George C. Marshall Space Flight Center.

Results of experimental work on annular plasma columns are presented. The plasma density was determined by measuring the dipole resonance using a section of a stripline. Results of the stripline measurement were used to locate the passband of the backward surface wave. The theoretically predicted forward and backward surface waves were measured. Agreement between the theory and the experiment is excellent. Theoretical consideration is given to a possible spurious oscillation resulting from electron beam interaction with the plasma body wave and a criterion for the existence of backward wave in a plasma column. Experimental results are presented of the measurement of the conductivity of pyrolytic graphiteBN layered material. The real part of the effective conductivity measured for one sample was 0.006 mho/meter. This value of the conductivity represents a possible improvement of 100000 in the loss characteristics of microwave slow-wave circuits built with this material over the pyrolytic graphite structures previouly discussed.