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Coal comprises about 50 percent of the conventional energy resources and about 70 percent of the fossil energy resources of the world. Asia contains about 50 to 70 percent of the total estimated coal resources of the world. The western Pacific basin of the Circum-Pacific Region contains about 20 percent of the world's total coal resources and is estimated to contain about 50 percent of the presently recoverable coal reserves of the world. Coal supplies about 27 percent of the world's primary energy production and provides about 56 percent of the primary energy production of the western Pacific basin. Among the nations of the area, China, Australia, New Zealand, and Vietnam produce more coal than they consume. Japan, both Koreas, the Philippines and Thailand consume more coal than they produce. Within the area as a whole, coal production and consumption are both about 30 percent of the world totals. Between 1981 and 1990, primary energy consumption in the basin increased by about 150 percent, and coal consumption increased by almost 170 percent. Both energy and coal consumption are expected to increase over the next three decades as nations of the region expand their economies and focus on indigenous coal resources as a basic energy supply. Within the western Pacific basin, the amount of information concerning coal resource potential ranges widely. Some nations (for example, Japan) place all their estimated coal resources in the proven­ in-place reserve category, while others (for example, Malaysia) place only a few percent in that category. While estimates vary, depending on the philosophy and practices used, it is probable that, in many cases, the available coal database is inadequate for reliable resource assessment. Increased exploration and development activities are needed to permit realistic and accurate evaluation of energy-planning options in the basin.

Recent experience with SLC (Stanford Linear Collider) has shown that very fast, ferrite-loaded, transmission-line, beam-kicker magnets can cause significant and undesirable distortion of a 1.5-2.5-kA, 20-40-kV pulse as it travels through the magnet. In general, there is a net lengthening of the pulse, with increases in its rise and fall times, a decrease in amplitude, and an unsymmetrical rounding of the flat top. A number of practical design considerations are discussed in terms of equivalent circuits, magnet circuit dispersion and dissipation, undesired circuit shunting and coupling, high-voltage breakdown problems and high-order-mode losses that lead to beam tube heating. These effects are linked to the properties of the materials, the presence of radiation, and realizable magnet topologies. Measurements and calculations of some of these characteristics for several magnet design are reviewed. >

The SLC (SLAC Linear Collider) ring kicker magnets require a fast magnetic field rise time of 58 nsec, a peak field of 800 gauss, a pulse amplitude stability of 0.01%, and a reasonable operational lifetime. The original kicker magnets designed by SLAC and at Fermi were not able to fulfil the SLC kicker requirements. Extensive studies were conducted to determine the limitations in the magnets, response of the ferrite in the kicker magnet, and the modifications needed to improve the kicker magnet performance. The basic physics of ferrite kickers, the magnet types, the ferrite material, the stray fields, and field compression are discussed in the context of the SLAC and Fermi kicker magnet limitations of performance. >

Coal is reported to be present in almost all the countries that border the Caribbean Sea. All the countries of Central America are known to contain coal except Belize. All the countries of northern South America contain coal except the Netherlands Antilles and Aruba. All the countries of the Greater Antilles contain coal, but among the island nations of the Lesser Antilles, only Anguilla has been reported to contain coal or coaly material.

Each klystron of the SLAC accelerator feeds four consecutive 10-foot accelerator sections through approximately 25 feet of earth shielding. The high power waveguide network which divides and guides the power to the four sections is adjusted so that the rf waves traveling within the accelerator sections are, at the end of each section, phased within ± two degrees of an ideal wave traveling at the velocity of light. A modulated reflection technique is used to compare the electrical phase length from a single input port through the four arms of the network during adjustment. The inclusion of the previously tuned accelerator sections in the network allows the total phase error to be minimized if careful control is exercised over the section terperatures. The measuring system, the reflection modulators, and the possible errors involved are discussed.

A study to determine the optuimum slow wave structure for a superconducting linear accelerator is being conducted. Vacuum, thermal, and mechanical problems at cryogenic temperatures impose limitations on such structures. Ultimately, the maximum energy gradient in a superconducting structure is limited by the critical magnetic field or electric field breakdown. At present a ?/2, biperiodic, standing-wave structure is favored. Calculations of the dispersion diagram and longitudinal electric field profile has been obtained from a coupled resonator, normal mode analysis. A comparison is made with room temperature measurements on stacked test cells. The effects of full end cells and of incorrectly tuned cells on the flatness of the electric field profile are considered. The relationship between cell tuning and the presence of a stop band in the dispersion curve is shown. Problems of coupling to a high Q superconducting structure and tuning the frequencies of sections in a multi-section linac are considered. Results are given for the Q, the dispersion diagram, and the energy gain for a 952 MHz lead-plated superconducting structure 5 feet in length operating near 2°K.

The Central Control Room for the MIT Linac is designed for simplicity of operation (one man) with an eye on future use of a computer to set the desired operating parameters. A natural summing of local controls around the five RF driver/dual-modulators and the injector/master oscillator control room allows one to switch to the display and control of the six areas one at a time with a trunk line. The distributed parameters (magnetics, radiation and RF phase monitoring) are mostly monitored and controlled directly from CCR with pushbutton selection of each parameter. Also mentioned are the detailed results of RF processing the 7m, S-band accelerator sections with 15ps, 4MW pulses at repetition rates exceeding 1000 s-1 and phase tuning the rectangular waveguide networks using a combination of the SLAC method and beam loading maximization.

A beam position monitor (BPM) for a storage or damping ring may be subject to heating problems due to the parasitic mode (PM) losses, beam interception and synchrotron radiation interception. In addition, high PM losses can cause beam instabilities under some conditions. Recessing and/or masking the BPM may increase the PM losses in the process of solving the latter two problems. This paper presents three complementary methods for estimating the PM losses and for improving the design of a stripline directional coupler type of BPM: bench measurements, computer modeling (TBCI) and an equivalent circuit representation. These methods lead to a decrease in PM losses without significant reduction in output signal for the north SLC damping ring BPMs.

A lasertron (a microwave "triode" with an RF output cavity and an RF modulated laser to illuminate a photocathode) is a possible high power RF amplifier for TeV linear colliders. As the first step toward building a 35 MW, S-band lasertron for a proof of principle demonstration, a 400 kV dc diode is being designed with a GaAs photocathode, a drift-tube and a collector. After some cathode life tests are made in the diode, an RF output cavity will replace the drift tube and a modelocked, frequency-doubled, Nd:YAG laser, modulated to produce a 1 us-long comb of 60 ps pulses at a 2856 MHz rate, will be used to illuminate the photocathode to make an RF power source out of the device. This paper discusses the plans for the project and includes some results of numerical simulation studies of the lasertron as well as some of the ultra-high vacuum and mechanical design requirements for incorporating a photocathode.

Successful operation of the Stanford Linear Collider (SLC) will require greater phase stability from the two-mile long RF drive network than previous linac operation did. This paper discusses four proposed modifications of the present system that should help achieve the general objective to reduce all long term temperature and atmospheric pressure induced phase variations to less than 20° at 2856 MHz, so that the phase/amplitude detector subsystems, which will control the network output phases relative to a beam reference, will operate within their most accurate ranges.

Bench measurements of the parasitic model loss parameter k, due to the interaction of a bunched beam with discontinuities in the vacuum pipe, are presented for many of the PEP beamline components. The measurements were made using the pulsed, coaxial transmission method of Sands and Rees. Full-scale machined and sheet metal models containing tapers, gaps, tanks (cavities), collimators, plates, electrodes and other irregular shapes were investigated. Accuracies, errors and modeling difficulties are pointed out. Loss curves and rules of thumb are discussed that should aid in the design of similar components. Also described is a moderately successful effort to de-Q some of the resonances in a particularly complicated chamber (separating plates) with a strip line coupling loop that is externally terminated at both ends.

A RF phase reference line in 6 segments around the 2200 meter circumference PEP storage ring is described. Each segment of the reference line is phase stabilized by its own independent feedback system, which uses an amplitude modulated reflection from the end of each line. The modulation is kept small and decoupled from the next segment to avoid crosstalk and significant modulation of the RF drive signal. An error evaluation of the system is made. The technical implementation and prototype performance are described. Prototype tests indicate that the phase error around the ring can be held below 1 degree with this relatively simple system.

A subsampling mill was constructed with 19 subsample spouts similar to the 1 or 2 subsample spouts on the conventional subsampling mills. Samples of peanuts, each of which contained 1 kernel made radioactive by neutron activation, were comminuted in the mill. For treatment M the discharge from each spout was kept separate. For treatment R, the discharge from all 19 spouts was blended together in a twin-shelled blender and subdivided with a riffle divider into 16 subsamples which averaged the same weight as the M subsamples. Radioactivity counts/gram of each subsample were measured. Eleven samples were comminuted for each treatment which produced a total of 209 M samples and 176 R samples. An analysis of variance on the pooled data from each treatment showed a mean square error of 1318.3 for the M treatment and 1278.6 for the R treatment. The null hypothesis that the mean square errors for the two treatments are equal was not rejected by the F test (P=0.421).

In order to minimize the size and weight of the x-ray or neutron source for a series of portable radiographic linear accelerators, the x-ray head was packaged separately from the rest of the system and consists of only the linac accelerating structure, electron gun, built-in target, collimator, ion pump and an RF window. All the driving electronics and cooling are connected to the x-ray head through flexible waveguide, cables, and waterlines. The x-ray head has been kept small and light weight by using the RF fields for radial focusing, as well as for longitudinal bunching and accelerating the beam. Thus, no external, bulky magnetic focusing devices are required. The RF focusing is accomplished by alternating the sign of the phase difference between the RF and the beam and by tapering from cavity to cavity the magnitude of the buncher field levels. The former requires choosing the right phase velocity taper (mix of less than vp=c cavities) and the latter requires the right sizing of the cavity to cavity coupling smiles (irises).

Three light-weight, x-band, electron accelerators have been developed to provide a series of highly portable sources of x-rays and neutrons for nondestructive testing. The 1.5 MeV x-ray unit has a 200 kW magnetron for an RF source and an air-cooled, traveling wave accelerating structure to minimize Its weight. The 4 and 6 MeV units share the same drive system which contains a 1.2 MW magnetron. The 4 MeV unit uses a traveling-wave guide to produce x-rays and the 6MeV unit uses a standing-wave guide to produce x-rays or neutrons. The choice of 9.3 GHz was dictated by the availability of a high power coaxial magnetron and by the obvious dimensional and weight advantages of a higher frequency over the more common S-band frequencies around 3 GHz.

A high degree of RF phase stability, throughout a high-average-power, physically large, microwave system requires careful attention to the design of the mechanical joints, supports and anchors, and of the numerous branches of its widely dispersed heat transfer network. The major designs discussed are: the 180m long coaxial drive line supports, anchors and thermal enclosure (for ± 1° phase stability,), the rectangular and disk loaded waveguide heat transfer and mechanical support designs, and the two 190 1/s cooling water systems that are designed to maintain temperatures at 36 ± 0.9°C and 45 ± 0.1°C, respectively.

The RF design objective for the MIT medium energy, high-duty-cycle linear accelerator has been to optimize and extend existing technology to obtain a degree of phase stability not previously achieved with high power RF systems. The RF system, which operates with a maximum average RF power of 80 kW per high power klystron (4 MW peak at 2% duty cycle to 1 MW peak at 6.5% duty cycle), is described. Accurate phase bridge measurements on the system indicate a pulse-top phase stability of better than 10 at 2856 MHz.

One approach to the problem of generating signals in the submillimeter range is to start from the large outputs available both at centimeter wavelengths or below one micron wavelength, and synthesize them by using non-linear media. The first alternative involves harmonic generation of microwave fundamental frequencies, and experience has shown that it is very difficult to obtain acceptable conversion efficiency above doubling or tripling. The second approach has become possible since the advent of high power masers in the optical and near infrared regions of the spectrum. These signal generators are capable of pulsed outputs of many kilowatts, and their frequency stabil ity is quite sufficient to provide monochromatic beat notes at wavelengths thousands of times larger.

Accelerator operation during the first year of scheduled beam to physics experiments is described. Some details of the gun, RF, water, vacuum, control and monitoring systems are reviewed with reference to performance and reliability.