Results of post-test psychological examinations of the crewmen from the 90-day manned test of an advanced regenerative life support system

The following material presents the results of two temporally remote administrations of an identical projective personality assessment device (Rorschach Inkblot) using crew members aboard the 90-day test. The first administration took place during preselection crew psychodiagnostic testing in the period extending from mid-December 1969 through mid-January 1970. Second administration took place in late May and early June, 1971, approximately one year after termination of the test. During the 90-day program duration, the subjects participated in the crew training program, were selected and served as onboard crew during the 90-day test. The testing was undertaken in order to determine the character and extent of change (if any) in basic personality dynamics accompanying or caused by participation in the 90-day test program. Results indicate that significant personality changes occurred in three of the four onboard crew members. A detailed discussion of the results is provided. Objective scores which served as the basis for the discussion are presented in the Appendix

SLC beam dynamics issues

The Stanford Linear Collider (SLC){sup 1,2} accelerates single bunches of electrons and positrons to 47 GeV per beam and collides them with small beam sizes and at high currents. The beam emittances and intensities required for present operation have significantly extended traditional beam quality limits. The electron source produces over 10{sup 11} e{sup {minus}} in each of two bunches. The damping rings provide coupled invariant emittances of 1.8 {times} 10{sup {minus}5} r-m at 4.5 {times} 10{sup 10} particles. The 50 GeV linac has successfully accelerated over 3 {times} 10{sup 10} particles with design invariant emittances of 3 {times} 10{sup {minus}5} r-m. The collider arcs are now sufficiently decoupled and matched in betatron space, so that the final focus can be chromatically corrected, routinely producing spot sizes ({sigma}{sub x}, {sigma}{sub y}) of 2.5 {mu}m at the interaction point. Spot sizes below 2 {mu}m have been made during tests. Instrumentation and feedback systems are well advanced, providing continuous beam monitoring and considerable pulse-by-pulse control. The luminosity reliability is about 60%. Overviews of the recent accelerator physics achievements used to obtain these parameters and the present limiting phenomena are described for each accelerator subsystem

Iris tilting and RF steering in the SLAC Linac

For some time now, the sources of RF transverse beam steering in the SLAC Linac have been a mystery. The previously known sources, coupler asymmetries and survey misalignment, have predicted deflections which are frequently much smaller than the observed deflections. A new source of RF steering has been discovered: the tilting of accelerator irises. Measurements of iris tilting in a forty foot accelerator girder are compared with measurements of RF beam deflections and are found to be strongly correlated. 4 refs., 6 figs., 3 tabs

Observations of the beam-beam interaction

The observed complexity of the beam-beam interaction is the subject of this paper. The varied observations obtained from many storage rings happen to be sufficiently similar that a prescription can be formulated to describe the behavior of the luminosity as a function of beam current including the peak value. This prescription can be used to interpret various methods for improving the luminosity. Discussion of these improvement methods is accompanied with examples from actual practice. The consequences of reducing the vertical betatron function (one of the most used techniques) to near the value of the bunch length are reviewed. Finally, areas needing further experimental and calculational studies are pointed out as they are uncovered

Beam dynamics issues in linear colliders

The primary goal of present and future linear colliders is to maximize the integrated luminosity for the experimental program. Beam dynamics plays a central role in the maximization of integrated luminosity. It is the major issue in the production of small beam sizes and low experimental backgrounds and is also an important factor in the production of particle numbers, in the acceleration process, and in the number of bunches. The beam dynamics effects on bunches which are extracted from the damping rings, accelerated in the linac, collimated, momentum analyzed, and finally delivered to the final focus are reviewed. The effects of bunch compression, transverse and longitudinal wakefields, BNS damping, energy definition, dispersion, emittance, bunch aspect ratio, feedback, and stability are all important. 11 refs., 1 tab

Mutual compensation of wakefield and chromatic effects of intense linac bunches

Mutual compensation of transverse and chromatic effects for intense electron bunches in a high-energy linac is a recent Novosibirsk idea which provides a new control of emittance enlargement. In this paper we elaborate on the principles and constraints for this new technique which requires careful matching of internal bunch parameters with external forces. With species values of the bunch length, bunch intensity, and klystron phasing, the transverse-wakefield-induced forces within the bunch can be cancelled by energy-dependent forces from the quadrupole lattice at all positions along the linac. Under these conditions the tolerances for quadrupole alignment, dipole stability, and injection launch errors are significantly relaxed. 7 refs., 8 figs

First Observations of a "Fast Beam-Ion Instability"

We report the results of experiments on a "fast beam-ion instability" at the Advanced Light Source (ALS). This ion instability, which can arise even where the ions are not trapped over multiple beam passages, will likely be important for many future accelerators. In our experiments, we filled the ALS storage ring with helium gas, raising the pressure approximately two orders of magnitude above the nominal value. With gaps in the bunch train large enough to avoid conventional (multi-turn) ion trapping, we observed a factor of 2-3 increase in the vertical beam size along with coherent beam oscillations. The single-pass nature of this instability was demonstrated

Effect of wakefields on first order transport in the SLC linac

The limitation in increasing the beam current in the SLC linac comes from the emittance growth caused by wakefields. Simulations of the beam transport that model the wakefield dynamics are being done to study methods to control this growth. To verify the theoretical estimates of the wakefield strengths assumed in these simulations, data were taken which are sensitive to their effect on the first order linac transport. Specifically, the dependence of single beam loading and betatron motion on beam current was measured in the range of 0--5.10{sup 10} to 3.5--10{sup 10} electrons per bunch. This paper presents these data together with comparisons to results from simulations. 5 refs., 7 figs