34 research outputs found
Consequences of spontaneous reconnection at a two-dimensional non-force-free current layer
Magnetic neutral points, where the magnitude of the magnetic field vanishes
locally, are potential locations for energy conversion in the solar corona. The
fact that the magnetic field is identically zero at these points suggests that
for the study of current sheet formation and of any subsequent resistive
dissipation phase, a finite beta plasma should be considered, rather than
neglecting the plasma pressure as has often been the case in the past. The
rapid dissipation of a finite current layer in non-force-free equilibrium is
investigated numerically, after the sudden onset of an anomalous resistivity.
The aim of this study is to determine how the energy is redistributed during
the initial diffusion phase, and what is the nature of the outward transmission
of information and energy. The resistivity rapidly diffuses the current at the
null point. The presence of a plasma pressure allows the vast majority of the
free energy to be transferred into internal energy. Most of the converted
energy is used in direct heating of the surrounding plasma, and only about 3%
is converted into kinetic energy, causing a perturbation in the magnetic field
and the plasma which propagates away from the null at the local fast
magnetoacoustic speed. The propagating pulses show a complex structure due to
the highly non-uniform initial state. It is shown that this perturbation
carries no net current as it propagates away from the null. The fact that,
under the assumptions taken in this paper, most of the magnetic energy released
in the reconnection converts internal energy of the plasma, may be highly
important for the chromospheric and coronal heating problem
PROFIL WISATAWAN MUSEUM RADYA PUSTAKA SURAKARTA
Anggit Margaret, C9407031 2011. Profil Wisatawan Museum
Radya Pustaka Surakarta. Program Studi Diploma III Usaha Perjalanan
Wisata Fakultas Sastra Dan Seni Rupa Universitas Sebelas Maret Surakarta.
Penelitian tugas akhir ini mengkaji tentang Profil Wisatawan di
Museum Radya Pustaka Surakarta. Tujuan dari penelitian ini adalah untuk
mengetahui dari daerah mana saja wisatawan yang berkunjung ke Museum
Radya Pustaka, bagaimana ciri-ciri wisatawan yang berkunjung ke Museum
Radya Pustaka serta harapan-harapan yang diinginkan wisatawan terhadap
Museum Radya Pustaka.
Penelitian dilakukan dengan metode kualitatif. Pengumpulan data
dilakukan melalui wawancara dengan narasumber wisatawan yang berkujung
di Museum Radya Pustaka Surakarta tempat penulis melakukan penelitian,
serta studi pustaka dan studi dokumen guna menambah sumber data.
Hasil penelitian menunjukkan bahwa (1) Sebagian besar wisatawan
yang datang berasal dari Semarang sebesar 32%. (2) Mayoritas wisatawan
yang berkunjung ke Museum Radya Pustaka berusia antara 17-25 tahun dan
kebanyakan dari mereka adalah pelajar atau mahasiswa dengan prosentase
52%. (3) Sebagian besar wisatawan yang datang ke Museum Radya Pustaka
adalah bertujuan untuk melakukan penelitian yaitu sebesar 34%. (4) Harapan
wisatawan yang berkunjung terhadap kelangsungan Museum Radya Pustaka
sebagian besar adalah agar ditingkatkan lagi pengelolaan dan keamanan
museum, agar kejadian hilangnya benda-benda koleksi museum tidak terulang
lagi dikemudian hari.
Kesimpulan dari hasil penelitian ini bahwa wisatawan yang berkujung
ke Museum Radya Pustaka Surakarta mayoritas berasal dari Semarang,
mayoritas berusia 17-25 tahun dan kebanyakan dari mereka adalah berprofesi
sebagai pelajar dan mahasiswa. Kebanyakan wisatawan yang datang bertujuan
untuk melakukan penelitian, serta harapan wisatawan terhadap Museum
Radya Pustaka adalah supaya lebih ditingkatkan lagi pengelolaan dan
keamanan museum
Basic topological elements of coronal magnetic fields
We model the magnetic field of a coronal active region using discrete magnetic sources and look for regions of the photospheric inversion line which are tangentially touched by coronal field lines. These locations are called 'Bald Patches'. Field lines threading these bald patch regions, together with those threading any coronal null points, determine the 'Topological Skeleton' of the field. We examine the properties of these null points and bald patch regions for two, three and four magnetic sources, and study the evolution of the coronal topological skeleton as a result of moving and varying the sources. In particular, for a four-source magnetic configuration, we establish the existence of a well-defined 'separator' field line in the absence of any coronal null points. We conclude that bald patches as well as coronal nulls constitute an elemental topological feature of the coronal field: they may be significant as possible regions for coronal current sheet formation and for prominence formation.</p
Basic topological elements of coronal magnetic fields
We model the magnetic field of a coronal active region using discrete magnetic sources and look for regions of the photospheric inversion line which are tangentially touched by coronal field lines. These locations are called 'Bald Patches'. Field lines threading these bald patch regions, together with those threading any coronal null points, determine the 'Topological Skeleton' of the field. We examine the properties of these null points and bald patch regions for two, three and four magnetic sources, and study the evolution of the coronal topological skeleton as a result of moving and varying the sources. In particular, for a four-source magnetic configuration, we establish the existence of a well-defined 'separator' field line in the absence of any coronal null points. We conclude that bald patches as well as coronal nulls constitute an elemental topological feature of the coronal field: they may be significant as possible regions for coronal current sheet formation and for prominence formation.</p
A trilinear method for finding null points in a three-dimensional vector space
Null points are important locations in vector fields, such as a magnetic
field. A new technique (a trilinear method for finding null points) is
presented for finding null points over a large grid of points, such as those
derived from a numerical experiment. The method was designed so that the null
points found would agree with any fieldlines traced using the commonly used
trilinear interpolation. It is split into three parts: reduction, analysis and
positioning, which, when combined, provide an efficient means of locating null
points to a user-defined sub-grid accuracy. We compare the results of the
trilinear method with that of a method based on the Poincare index, and discuss
the accuracy and limitations of both methods.Comment: 12 pages, 4 figures, submitted to Physics of Plasma