| 1. |
- Bødker, Anders, et al.
(författare)
-
Estrogen receptors in the human male bladder, prostatic urethra, and prostate. An immunohistochemical and biochemical study
- 1995
-
Ingår i: Scandinavian Journal of Urology and Nephrology. - : Informa UK Limited. - 0036-5599 .- 1651-2065. ; 29:2, s. 161-165
-
Tidskriftsartikel (refereegranskat)abstract
- The distribution and quantity of estrogen receptors (ERs) in the human male bladder, prostatic urethra and the prostate were studied in eight males with recurrent papillomas of the bladder or monosymptomatic hematuria (median age 61 years), 14 men undergoing transurethral resection due to benign prostatic hyperplasia (median age 70 years), and nine men undergoing cystectomy due to malignant tumour of the bladder (median age 70 years). In the first group of patients, biopsies for immunohistochemical examination were obtained from the bladder vault, bottom, both side-walls, the trigone area, and the mid-portion of the prostatic urethra, and in the second group from three locations of the prostatic urethra (bladder neck, mid-portion and veramontanum). In the third group, tissue specimens were taken from the vault of the bladder, prostatic urethra, and the prostate, for immunohistochemical as well as biochemical analysis. In the first group, ERs were found in three out of eight specimens of the prostatic urethra, and in one of these, ERs were confined to periurethral glands. ERs could not be demonstrated in any of the bladder-biopsies. In the second group, ERs were not found in the bladder neck, but were seen in four preparations from the veramontanum and in two from the midportion of the urethra. ERs were located in the urothelium and periurethral glands. In the third group, ERs were seen immunohistochemically in the prostatic urethra (two cases) and the prostatic stromal tissue (two cases). ERs could be demonstrated in the bladder neither by immunohistochemistry nor biochemically.(ABSTRACT TRUNCATED AT 250 WORDS)
|
|
| 2. |
- Belfrage, Hans, et al.
(författare)
-
Enhanced and prolonged efficacy of superantigen-induced cytotoxic T lymphocyte activity by interleukin-2 in vivo
- 1995
-
Ingår i: Cancer Immunology and Immunotherapy. - 1432-0851. ; 41:2, s. 87-94
-
Tidskriftsartikel (refereegranskat)abstract
- The bacterial superantigen, staphylococcal enterotoxin A (SEA) activates T cells with high frequency and directs them to lyse MHC-class-II-expressing cells in superantigen-dependent cell-mediated cytotoxicity (SDCC). Treatment of mice with SEA induced strong CD8+ T-cell(CTL)-mediated SDCC, as well as abundant cytokine production from CD4+ and CD8+ T cells. However, both cytotoxicity and cytokine release were transient. In contrast, combined treatment with SEA and recombinant interleukin-2 (rIL-2) increased peak levels and maintained CTL activity. These effects were concomitant with an increased number of SEA-reactive V beta 11+ T cells. Both the CD4+ and CD8+ populations contained higher frequencies of cells expressing IL-2 receptor (IL-2R) alpha beta, which suggests that continuous IL-2R signaling preserves its high expression and subsequently prevents loss of growth factor signals necessary for expansion of T cells. Although IL-2R expression was increased among both CD4+ and CD8+ cells, only the cytotoxic function of CTL, but not cytokine production from either CD4 or CD8, was augmented. These findings demonstrate that treatment with rIL-2 potentiates superantigen-induced cytotoxicity and maintains high CTL activity. rIL-2 might therefore be useful in improving superantigen-based tumor therapy.
|
|
| 3. |
- Belfrage, Hans, et al.
(författare)
-
Prevention of superantigen induced down-regulation of T cell mediated cytotoxic activity by IL-2 in vivo. 1996 Accepted for publication in Immunology
- 1997
-
Ingår i: Immunology. - 0019-2805. ; 90:2, s. 8-183
-
Tidskriftsartikel (refereegranskat)abstract
- Administration of staphylococcal enterotoxin A (SEA) to mice induces profound activation, cytokine production and cytotoxic activity of both CD4+ and CD8+ T cells, but subsequently activated cells are deleted or become anergic. This study demonstrates that administration of interleukin-2 (IL-2) can prevent sea-induced hyporesponsiveness in CD8+ cytotoxic T lymphocytes (CTL). Repeated injections with sea every fourth day resulted in severely reduced cytotoxic activity in the spleen, which correlated with a reduced number of sea-responsive T-cell receptor (TCR)-V beta 11+ CD8+ cells. Studies of purified TCR-V beta 11+ CD8+ cells showed that they possessed intact cytotoxic activity per cell compared with cells from mice given a single injection of SEA, indicating that deletion was the main mechanism for the reduced cytotoxic activity. Combined treatment with SEA and IL-2 increased the number of cytotoxic cells in the spleen after each SEA injection and prevented the down-regulation of cytotoxic activity. Increased cytotoxic activity could be related to increased number and proliferation of CD8+ IL-2R alpha + cells, suggesting that administration of IL-2 maintained IL-2 responsiveness among CD8+ cells. Studies of sorted TCR-V beta 11+ CD8+ cells demonstrated that combined treatment with SEA and IL-2 also increased cytotoxic activity per cell compared with treatment with SEA alone. Taken together, IL-2 administration in vivo augmented SEA-induced expansion of T cells as well as the cytotoxic activity per CTL, and prevented SEA-induced cell deletion.
|
|
| 4. |
- Belfrage, Hans, et al.
(författare)
-
Prevention of superantigen-induced tolerance in vivo by interleukin-2 treatment. 1996 Submitted
- 1997
-
Ingår i: Cancer Immunology and Immunotherapy. - 1432-0851. ; 44:2, s. 77-82
-
Tidskriftsartikel (refereegranskat)abstract
- Injection of the superantigen staphylococcal enterotoxin A (SEA) activates both CD4+ and CD8+ T cells expressing certain families of T cell receptor (TCR) variable-region beta (V beta) chain. T cells respond with profound cytokine production and induction of cytotoxicity. Repeated injections, however, cause deletion and anergy of both CD4+ and CD8+ T cells, resulting in reduced frequency of SEA-responsive cells TCR-V beta11+ as well as reduced cytokine levels in serum upon challenge with SEA. Exogenous interleukin-2 (IL-2) in vivo rescued SEA-responsive CD4+ and CD8+ cells from SEA-induced deletion and/or increase expansion of SEA-primed cells as well as preventing downregulation of endogenous IL-2 production in vivo. Combined treatment with SEA and IL-2 also superinduced production of important cytokines for the cytotoxic function of T cells, tumour necrosis factor alpha, interferon gamma and IL-6, on a cellular level. These studies show that continuous stimulation with IL-2 in vivo could be useful for superantigen-based immunotherapy by induction of excessive T cell activation and by prevention of the development of T cell deletion and anergy.
|
|
| 5. |
- Bjorklund, Robert B., et al.
(författare)
-
Vapor adsorption in thin silicalite-1 films studied by spectroscopic ellipsometry
- 1998
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 102:12, s. 2245-2250
-
Tidskriftsartikel (refereegranskat)abstract
- Thin films of silicalite-1 grown on silicon substrates were studied by spectroscopic ellipsometry. Analysis of spectra using an optical model consisting of a single porous layer on silicon yielded average film thicknesses of 84 and 223 nm for films synthesized for 10 and 30 h. Void fraction for the films was 0.32-0.33. Vapor adsorption from a nitrogen carrier gas at room temperature was monitored by ellipsometry. Isotherms for different adsorbates were obtained by analysis of spectra taken at different vapor concentrations using an optical model where the void volume was filled with both nitrogen and condensed vapors. Quantification of the condensed vapor amount was based on the changes in refractive index when adsorbates replaced nitrogen in the pores. Adsorbate volumes for water, toluene, 1-propanol, and hexane were 0.12, 0.12, 0.15, and 0.17 cm3 liquid g-1 film, respectively.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Groth, Patrik, et al.
(författare)
-
Air cooling of concrete by means of embedded cooling pipes—Part II: Application in design
- 1998
-
Ingår i: Materials and Structures. - 1359-5997 .- 1871-6873. ; 31:210, s. 387-392
-
Tidskriftsartikel (refereegranskat)abstract
- This paper relates the second part of the investigation of air-cooling in concrete; the first part is presented in `Air cooling of concrete by means of embedded cooling pipes Part I: Laboratory tests and heat transfer coefficients'. Embedded cooling pipes are used to reduce the risk of thermal cracking in early age concrete. Traditionally, water has been used as a cooling medium, but air cooling has been shown to be advantageous for many applications. The experimentally-determined heat transfer coefficients of cooling pipes, have been used and verified in comparisons of in situ measurements at the Igelsta Bridge in Sodertalje, Sweden. The close agreement between measured and calculated temperatures of air-cooled sections seems to justify the use of the averaged heat transfer coefficients determined in [1]. Some exemplifying calculations are also shown, and the general behaviour of cooled structures is discussed. The principles of designing a cooling system for a general case are proposed. It is concluded that it is possible to design prismatic structures, such as a columns, by the use of existing models and measured heat transfer coefficients
|
|
| 11. |
- Groth, Patrik, et al.
(författare)
-
Luftkylning av betong med ingjutna kylrör
- 1996
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten inleds med en sammanfattande genomgång av tidigare genomfört arbete inom detta projekt vilket redovisas i kapitel 2. Kapitel 3 innefattar en redovisning av de fältmätningar som utförts inför denna del av projektet på Igelstabrons enkelspårspelare. Som en uppföljning till fältmätningarna har även laboratorieförsök utförts i syfte att finna värmeövergångstal för kylrör, dessa återfinns i kapitel 4. Till sist har ett antal beräkningar avseende temperaturer och temperaturspänningar genomförts vilka visar en jämförelse mellan uppmätta och beräknade resultat och en del exempelfall vilket finns i kapitel 5. Bilaga A och B innehåller samtliga mätresultat från fältundersökningen och bilaga C innehåller en redovisning av de beräkningsverktyg, HETT2D och TEMPSTRE, som använts. Bilaga D innehåller samtliga resultat från laboratorieförsöken och i bilaga E redovisas de parametrar som använts i exempelberäkningarna.
|
|
| 12. |
- Hedlund, Christer, 1964-, et al.
(författare)
-
A Method for the Determination of the Angular Dependence during Dry Etching
- 1996
-
Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 14:5, s. 3239-
-
Tidskriftsartikel (refereegranskat)abstract
- Process simulation is going to play an ever increasing role in the development, process optimization, and production of integrated circuit devices, yielding shorter development times and reduced costs as compared to traditional development methods. One of the most notorious problems one faces in topography simulations in particular is the determination of the erosion/growth rates of materials exposed to a variety of complex physicochemical processes. The latter evolve continually to satisfy the needs of the ever advancing microelectronic industry, while our understanding about these processes is often incomplete and insufficient for their description. Existing theoreticalmodels, which are often semiempirical, include a set of fitting parameters which are generally unknown and their determination in most cases involves guesswork. Another much more pragmatical approach to the problem is to measure these etch/growth rates directly in situ in the production equipment and feed the data into a topography simulator. In this article we present a simple and general method for measuring the angular dependence of the etch rate of a variety of materials using specially patterned silicon wafers. With anisotropic wet etching of silicon wafers it is possible to create structures defined by specific crystallographic planes, thus producing a variety of planar orientations on one and the same wafer. The structures can be oxidized and coated with the material of interest and processed under standard operating conditions. The method will be presented together with angular dependence data from typical dry etching processes. The results will be used as an input to the topographysimulation program DINESE.
|
|
| 13. |
|
|
| 14. |
- Hedlund, Christer, 1964-, et al.
(författare)
-
Angular dependence of the polysilicon etch rate during dry etching in SF6 and Cl-2
- 1997
-
Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 15:3, s. 686-691
-
Tidskriftsartikel (refereegranskat)abstract
- The angular dependence of the etch rate in reactive ion etching (RIE) and inductively coupled plasma (ICP) systems for polysilicon etching with SF6" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">SF6SF6 and Cl2" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">Cl2Cl2 is determined using a recently developed direct measurement method. The latter utilizes specially patterned silicon groove structures consisting of 7–10 μm wide planar surfaces which form various angles with respect to the wafer normal. The structures are produced by highly anisotropic wet chemical etchingof Si through a gratinglike mask pattern aligned along specific crystallographic orientations of the wafer which results in the development of planar surfaces of various orientations. These surfaces are then coated with the materials to be studied—polysilicon in this case. The deposited polysilicon is then etched under a variety of conditions in a RIE and an ICP reactor and the etch rates determined by interferometric measurements. Since only standard Si wafers are used and the size of the pattern is only a few μm the method is fully IC production compatible, which means that one can measure the angular dependence of the etch rate directly in production etching systems. The results for RIE of polysilicon with SF6" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">SF6SF6 show that the process becomes more isotropic with increasing pressure. The angular dependence of the RIE and ICP polysilicon etchrates in Cl2" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">Cl2Cl2 atmosphere were found to vary with the substrate bias. Specifically low substrate bias resulted in an under cosine distribution whereas bias higher than 240–250 V led to over cosine distributions.
|
|
| 15. |
- Hedlund, Christer, et al.
(författare)
-
Angular dependence of the polysilicon etch rate during dry etching in SF6 and Cl-2
- 1997
-
Ingår i: JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS. - 0734-2101. ; 15:3, s. 686-691
-
Tidskriftsartikel (refereegranskat)abstract
- The angular dependence of the etch rate in reactive ion etching (RIE) and inductively coupled plasma (ICP) systems for polysilicon etching with SF6 and Cl-2 is determined using a recently developed direct measurement method. The latter utilizes specially
|
|
| 16. |
|
|
| 17. |
- Hedlund, Hans, et al.
(författare)
-
Air cooling of concrete by means of embedded cooling pipes-Part I: Laboratory tests of heat transfer coefficients
- 1998
-
Ingår i: Materials and Structures. - 1359-5997 .- 1871-6873. ; 31:5, s. 329-334
-
Tidskriftsartikel (refereegranskat)abstract
- Embedded cooling pipes can be used to reduce the temperature rise in massive structures as a measure against thermal cracking. When air is used as a cooling medium, relatively large diameters with profiles causing friction losses along the pipe are preferred. In this paper, heat transfer coefficients for two different types of cooling pipes have been determined for different pipe flows in combination with various temperature levels. This paper relates to the first part of the investigation dealing with the laboratory tests of heat transfer coefficients. The second part, dealing with application in design, is presented in "Air cooling of concrete by means of embedded cooling pipes-Part II: Applications in design"
|
|
| 18. |
- Hedlund, Hans, et al.
(författare)
-
Analysis of early age cracking in HPC structures
- 1999
-
Ingår i: Utilization of high strength/high performance concrete : proceedings. - Oslo : Norsk Betongforening. - 8291341257 ; , s. 1134-1143
-
Konferensbidrag (refereegranskat)
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
|
|
| 22. |
- Hedlund, Hans, et al.
(författare)
-
Grönare betong
- 1999
-
Ingår i: Bygg och Teknik. - 0281-658X .- 2002-8350. ; 91:7, s. 12-13
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
|
| 23. |
|
|
| 24. |
- Hedlund, Hans, et al.
(författare)
-
Hardening technology for concrete structures
- 1997
-
Ingår i: Advanced design of concrete structures. - Barcelona : International Center for Numerical Methods in Engineering (CIMNE). - 8487867944 ; , s. 313-318
-
Konferensbidrag (refereegranskat)
|
|
| 25. |
- Hedlund, Hans, et al.
(författare)
-
Härdningsstyrning av betongkonstruktioner
- 1996
-
Ingår i: Byggforskning : Byggforskningsrådets tidning för en bättre byggd miljö. - 1102-3686. ; :3, s. 38-39
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
- Hedlund, Hans, et al.
(författare)
-
Measurements of self-desiccation and shrinkage of hardening concrete
- 1997
-
Ingår i: Moisture Measurement in Concrete Constructions Exposed to Temperature and Moisture Variations. - Espoo : Valtion teknillinen tutkimuskeskus. Tie- ja liikennelaboratorio. - 9513845656 ; , s. 73-101
-
Konferensbidrag (refereegranskat)
|
|
| 29. |
- Hedlund, Hans Peter
(författare)
-
Kan konservering bli ekologisk?
- 1997
-
Ingår i: Kulturmiljövård. - Stockholm : Riksantikvarieämbetet. - 1100-4800. ; :4, s. 74-77
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Ett konserveringsmedel måste uppfylla långtgående krav på beständighet; det får inte påverka föremålets ytkaraktär eller orsaka förändringar, det måste kunna avlägsnas och får inte reducera föremålets värde eller utföra hinder för en omkonservering. -Beaktar vi dessa krav betyder god materialekologi inte att vi bör använda traditionella naturliga konserveringsmedel utan konserveringsmedel som är anpassade till sitt syfte, skriver Hans Peter Hedlund.
|
|
| 30. |
|
|
| 31. |
- Hedlund, Hans
(författare)
-
Stresses in high performance concrete due to temperature and moisture variations at early ages
- 1996
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents results from laboratory tests and numerical analyses of stress states in concrete structures arising from volume changes due to temperature and shrinkage during hydration. The laboratory tests presented here deal with: the determination of heat transfer coefficients for cooling pipes measurements of self-desiccation and shrinkage under sealed conditions deformation measurements under temperature and moisture changes and measurements of stress development during hardening for a fully restrained structural member. The thesis comprises three papers dealing with the following topics:Paper A - Air cooling of concrete by means of embedded cooling pipes. Laboratory tests of heat transfer coefficientsThis paper presents a laboratory method for determining heat transfer coefficients for cooling pipes. The embedded cooling pipes are used in order to reduce the temperature rise in massive structures as a measure against thermal cracking. When air is used as cooling medium, relative large diameters with surface profiles (roughness) causing friction losses along the pipe are preferable. Heat transfer coefficients for two different types of cooling pipes have been determined for varying pipe flows in combination with different temperature levels. Paper (A) constitutes the first part of the thesis dealing with the laboratory tests on heat transfer coefficients.Paper B - Air cooling of concrete by means of embedded cooling pipes. Application in designPaper B constitutes the second report on the subject air cooling of concrete. Embedded cooling pipes are used in order to reduce the risk of thermal cracking in early age concrete. Traditionally, water has been used as the cooling medium, but air cooling has shown to be advantageous in many applications. The experimentally determined heat transfer coefficients of cooling pipes, investigated in Paper A, have been used and verified in comparisons with in situ measurements at the Igelsta Bridge in Södertälje, Sweden. The close agreement between measured and calculated temperatures of air-cooled sections seems to justify the use of average heat transfer coefficients. A few exemplifying calculations are also given, and the general behaviour of cooled structures is discussed. The principles of designing cooling systems for the general case are proposed. It is concluded that it is possible to design prismatic structures, such as a columns, by the use of existing models and the measured heat transfer coefficients evaluated according to the method presented in Paper A.Paper C - Deformation and Stresses in Hardening Concrete due to Simultaneous Changes in Humidity and Temperature. Laboratory tests and evaluation This paper describes test methods and equipments for determination of strength and maturity growth, heat of reaction, and free thermal deformation. Measurements of shrinkage, relative humidity and stress development are carried out under sealed conditions during hardening of the young concrete. Results for both high performance and normal strength concretes are presented and discussed here. Also, methods for describing shrinkage at sealed conditions as a function of maturity and as a decrease in relative humidity are presented. An evaluation is performed of the free thermal deformation during the hardening of concrete where the deformation is separated into pure thermal deformation and shrinkage. In this context some pilot calculations of non-linear modelling of stress development have been performed taking stress-induced deformations and simultaneous changes in humidity and temperature into account. Calculations are made for a structural member which is fully restrained, i.e. to a degree of 100%. A sensibility analysis of the non-linear stress model is performed and presented.
|
|
| 32. |
|
|
| 33. |
- Johansson, Erik, et al.
(författare)
-
PHOTOVOLTAIC AND INTERFACIAL PROPERTIES OF HETEROJUNCTIONS COMPRISING DYE-SENSITIZED DENSE TiO2 AND TRIARYLAMINE DERIVATIVES IN SOLID AND LIQUID STATE.
- 1996
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Different triarylamine derivatives have successfully been used as solid hole-conductor materials in dye-sensitized solar cells with efficiencies up to 4% [1-3]. In the present work TiO2/dye/ hole-conductor heterojunctions is assembled to form model systems for solid state DSSC and the interfacial structure at the molecular level. A series of triarylamine molecules is used to investigate the influence of small differences in the hole-conductor material structure on the photovoltaic and molecular surface properties. Both solid state and liquid state junctions with the triarylamine molecules were investigated. In the solid state heterojunctions the hole-conductor molecules were evaporated on the substrate and in the liquid state heterojunctions the hole-conductor molecules were solvated in an organic solvent. The photovoltaic properties of the heterojunction largely depend on the electron transfer rates at the interfaces between the different materials (semiconductor, dye and hole-conductor). Photoelectron Spectroscopy (PES) measurements was used to investigate the molecular and electronic interface structure. In the figure below the valence electronic structure of interfaces with the different hole-conductors are shown.From the valence PES the interaction and the energy level matching between the dyes and the hole-conductors is studied. The results show large differences in the energy matching of the different holconducting materials with respect to the dye molecules partly explaining the differences in efficiency. The valence structure also shows that when combining different materials their individual properties adjust slightly to their new environment. From the core level PES we observe differences molecular surface structure. Specifically it was found that the smaller holecondctors are able to penetrate the dye layer and contact the TiO2 surface.
|
|
| 34. |
|
|
| 35. |
|
|
| 36. |
|
|
| 37. |
|
|
| 38. |
|
|
| 39. |
|
|
| 40. |
- Jonsson, Lars, et al.
(författare)
-
Controlled topography production - True 3D simulation and experiment
- 1995
-
Ingår i: Vacuum. - 0042-207X .- 1879-2715. ; 46, s. 971-975
-
Tidskriftsartikel (refereegranskat)abstract
- A true 3D computer program, named DINESE, has been developed to simulate the evolution of real 3D structures during erosion and deposition. It is based on the generalized Huygens reconstruction formalism of surface evolution and can predict the evolution of any surface of the form z = f(x,y) resulting from any erosion or deposition process. True 3D computer simulations of a number of cases are presented and compared with experiment. The powers of the simulation method are further demonstrated by a series of sequential predictive simulations resulting in a desired topography which is then verified experimentally under the same sequence of conditions. Specifically, the evolution of different Si3N4 structures during ion beam etching with Ar ions under different erosion conditions has been studied both numerically and experimentally.
|
|
| 41. |
|
|
| 42. |
|
|
| 43. |
|
|
| 44. |
|
|
| 45. |
|
|
| 46. |
|
|
| 47. |
|
|
| 48. |
- Shamrai, K P, et al.
(författare)
-
Discharge disruptions in a helicon plasma source
- 1997
-
Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 15:6, s. 2864-2874
-
Tidskriftsartikel (refereegranskat)abstract
- We study experimentally and theoretically stable regimes and dischargedisruptions in a helicon plasma source. At fixed input power and gas pressure, stable operation of the source is possible below some critical value of magnetic field Bcr." role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">Bcr.Bcr. The plasma density increases with the magnetic field and reaches a maximum value nmax" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">nmaxnmax at Bcr;" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">Bcr;Bcr; after which the discharge disruption occurs. Both Bcr" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">BcrBcr and nmax" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">nmaxnmax increase almost linearly with the input power and the rate of increase is increasing with the pressure. Matching of the plasma load to the rf power source improves when approaching the disruption point, and becomes perfect at the critical field. The theory of discharge disruptions assumes the power absorption in a helicon source to arise from the linear conversion of helicon waves into electrostatic waves at the plasma edge. The calculated dependence of the absorbed power on the plasma density turns out to be nonmonotonic with minima at antiresonances of the electrostatic waveexcitation. This explains qualitatively principal peculiarities of dischargedisruptions. The calculated plasma impedance is in agreement with experimental value within a factor of 2.
|
|
| 49. |
|
|
| 50. |
|
|
